The only income tax issue is who owe capital gains tax when the property is sold. Without any other information, the IRS will assume that the home was equally owned by the 3 owners, and when the home is sold, each owner will be responsible for 1/3 of the capital gains tax, if there is any tax owed (which will depend on a number of factors).
If you want to split the ownership up in any other way, see an attorney. If you have a disagreement about how to divide the tax owed, or divide the proceeds from the sale to take into account the other circumstances you mention, then you either need to agree among yourselves or see an attorney.
