Can a cohabitation agreement protect my children's inheritance from a previous relationship?

Yes. A cohabitation agreement can explicitly preserve assets you intend to leave to children from a previous relationship by treating those assets as your separate property and excluding them from any division or support claim if the common-law relationship ends. This is a primary reason many parents entering second or later relationships use domestic contracts.

For example, if you own a home or have investments that you intend to pass to your children from a prior relationship, the agreement can confirm that those assets remain yours alone, that any increase in their value remains yours, and that your partner has no claim to them at separation or through a trust-based claim. This protection is particularly important for common-law partners, who would not have an automatic equalization right to property anyway — but whose potential trust claims or support claims might still complicate your estate plan.

Estate planning documents — particularly your will — should work in harmony with the cohabitation agreement. A cohabitation agreement addresses what happens during your lifetime or at separation; your will addresses what happens on death. Having an estate lawyer and a family lawyer coordinate these documents ensures there are no gaps or conflicts. A dependant's relief claim by a surviving common-law partner is a separate risk that your estate plan should also address.