Ever since Michelle Triola Marvin filed suit against actor Lee Marvin demanding half of what he earned for the six years they lived together, the courts have been flooded with suits brought by disgruntled ex-lovers. Among those sued by former roommates are Alice Cooper, Nick Nolte, Peter Frampton and Rod Stewart. Now a young couple, Toni Ihara, 32, and Ralph Warner, 38, have compiled The Living Together Kit (Fawcett Crest, $2.50) for the more than two million people sharing housekeeping outside marriage. Their most important piece of advice is "Avoid lawyers." Ihara and Warner know their subject: Both are attorneys and have lived together for the past three years. Warner grew up in New York, graduating from Princeton in 1963. Once accepted by the University of California at Berkeley law school, he packed his wife and son into a 10-year-old station wagon and drove across the country. The marriage failed in 1966 ("Right after exams"), and a year later he remarried; that too ended in divorce. Ihara has never been married. A third-generation Japanese-American, she grew up in the Watts district of Los Angeles, got a B.A. from Berkeley and her law degree from the University of California at Davis. Ihara and Warner met when they were working for members of the Berkeley city council. For Dianna Waggoner of PEOPLE they talked about the legal aspects of cohabitation—from buying a house to making a will.

Do people living together without being married need contracts?

Yes. Often just the fact of drawing one up offers an opportunity to clarify their situation. It's a time to find out if they have different assumptions—who is going to support whom, for example, or whether income is going to be shared. When you're feeling good you can work out an arrangement more fairly than when you're under the stress of breaking up.

Doesn't making a contract imply that the partners don't trust each other?

Not really. Contracts have gotten a bad reputation because they've been used by the legal system to take things away from people. But you have to remember that you're not making a contract with GM or IBM. If you draw it up between yourselves there won't be any lawyers involved and no need to confuse the contract with fine print clauses or incomprehensible jargon.

What should the contract say?

The less complicated and more basic the better because everything is on the table. It should be written in clear language and signed at the bottom. If it involves property, the contract should be recorded at the county office. We think it's nuts to include who gets the bathroom scale or toaster, but some couples do.

Are self-drawn contracts legally enforceable everywhere?

Practically everywhere. There are still 15 states which have laws against unmarried adults living together, but few of them are likely to enforce the laws. For years the validity of contracts between unmarried adults was questioned by sanctimonious judges who didn't want to extend contract rights to people who were "living in sin." But this is no longer true.

Should gays sign such a contract?

Most of our advice applies equally to gay and straight couples. But there are some special problems. The majority of states still have laws against homosexual acts, and if one member of the couple wanted to void a contract, he or she might testify in court that homosexual conduct formed the basis of the agreement. Some judges might then refuse to enforce it. In general, however, courts will probably enforce living-together contracts between gays.

Should unmarried couples have joint bank accounts and credit cards?

Our advice is to keep your incomes separate. If you break up, it's much easier to pull things apart. Some couples feel a need to put their incomes together, and for these people we recommend separate bank accounts and credit cards, but a joint account for rent, telephone and utilities.

Are there any other reasons for keeping incomes separate?

Yes. If you have mixed everything together, it is difficult to prove to a creditor what belongs to whom. If you have a joint bank account a creditor may take one person's money to satisfy the other's debt, unless you can prove how much belongs to which partner. Keep it separate, and good luck to the bill collector.

What should an unmarried couple know about buying a house together?

First they should decide whose name the house will be in. If they choose to put both of their names on it they are faced with whether they will be "joint tenants" or "tenants in common." The basic difference is that if one joint tenant dies the other partner automatically takes the deceased person's share without probate proceedings. But if one tenant in common dies, unless the will provides otherwise, his or her share will go to the nearest blood relative.

What other decisions do couples have to make when buying a house?

They need to decide what happens to it if they split up—who should keep the house or whether it should be sold. The simplest way to handle the matter is to sell the house and divide the proceeds equally. However, if one person has put more money into the house, that person should receive more money from the sale. You can work all this out in a contract.

What are the legal aspects of having children outside marriage?

This is when most couples decide to get married. But being unmarried and having children is not dangerous legally—so long as you pay attention to the rules. You must make certain that paternity is absolutely clear because this can affect inheritance, Social Security and insurance benefits for the child. If a brick fell on Daddy's head, the child would have to prove paternity before collecting one cent.

How do you establish paternity?

Father and mother both sign a simple one-paragraph statement acknowledging parenthood. Each should keep one copy, and a third copy should be put in a safe place for the child.

What about making a will?

Unmarried couples should have a will or at least plan for death. In case of death your nearest blood relative, not your live-in mate, will inherit unless you provide otherwise. Most states allow for automatic inheritance by a spouse, but remember that the person you live with is not your spouse. A will is good for passing along personal property, but larger items—house, automobiles, land—should probably be put in joint tenancy.

Is there a tax advantage to living together rather than being married?

If the couple earns anywhere near the same amount of money there is probably a tax disadvantage if they marry. However, if one earns a lot more than the other, there is probably an advantage to marriage. This advantage increases if the person with the lower income has dependents.

How has the Lee Marvin case changed the idea of living together?

It has made having a contract more important than ever. The California supreme court said it would enforce written contracts. It will also look at the couple's relationship to make sure that property is divided according to their reasonable expectations—even if they don't have an agreement in writing. In order to prove the expectations of a couple the court could drag in every aspect of their relationship. It might be worse than any contested divorce.

Should people go to court to resolve their separation disputes?

Only as a last resort, because the legal system is used in an aggressive attempt to screw every last nickel out of an adversary. Some lawyers have evolved no further than the hired guns of Dodge City. They are the point men for a corrupt system having almost nothing to do with fairness, truth or the resolution of disputes. Drafting a contract may not seem very romantic, but it's a lot more romantic than being in superior court at 9 a.m. on Monday.

Do you two have a contract?

Yes. We have a one-page agreement which covers the proceeds from books we have written together. People need a contract for what is significant to them. In our case we have only a funky stereo, a dog, a cat and some flea market furniture. If we had a garage sale we'd make maybe $1,000.

What would happen if you broke up?

Toni and I love each other so much that if we ever do break up we like to think we'll do it with such style and grace that everything will work out. But, of course, that's impossible—if it's a long-term relationship it's bound to be messy. It's absolutely your worst moment. So you'd better be prepared.