The way TurboTax is set up, you don't enter the social security number for the third person., You can enter your percentages in amounts that all parties agree on. If the other parties also get a 1095-A they will enter your social security number as the person that they shared the policy with you.
The only rule is that all parties have to agree to the percentage amounts and that the percentages much add up to 100%.
So it could be 33/33/34, or 100/0, or any combination that adds to 100 and all agree upon.
The 1095-A is used to determine your Premium Tax Credit
