Legal Question in Real Estate Law in California

There are really two related questions here. The first is whether one co-owner can commit to expenditures that would become a charge against the financial interests in the property of the other co-owners upon a sale. The answer here is that it depends upon the necessity or urgency of the expenditure. Outlays for things like mortgage payments, insurance premiums, property taxes and "necessary repairs, " when made by co-owner #1, become latent claims against the other co-owners, if and when the property is sold and profits realized. The good neighbor fence in question MAY fall into this category. However, the other question is whether co-owner #1 can send the other co-owners a bill for their share and expect to collect, prior to a sale of the property where everyone cashes in. Here, I think it depends upon what the co-owners may have agreed upon -- any contract between them -- for the care and management of the property. If there is none, I think it is doubtful that any co-owner who didn't agree to pay could be forced to pay, prior to a sale of the property.