How do I report and claim a portion of the rent I collect?
This question is so complex and requires looking at any original documentation from grandmother on ownership of the property. You would need to talk to a tax expert to find out the logistics of portioning out the rent as well as determining the tax liability for each. It would be better to have one tax person do the breakout and give each of you an amount of income to report and then have the tax person determine your tax liability. This is a very complex question and the answer would be best asked and answered by a tax expert who has seen the paperwork on the rental/lease and the income. Do not rely on Quora to give you the best advice. This is a PERSONAL tax issue.