Capital Gains on Sell of Primary Residence that has Two Houses?

[Cheryl Platt]

We have three lots with two houses on them that are all deeded together and are covered under a single property tax bill. We lived in the large house and the guest house was lived in by my daughter and her family until recently. Each house has its own address and we can split the property into two properties and sell the houses separately. We already have two different buyers, one for each house. I'm trying to avoid capital gains tax since the "property" was our primary residence for all but the last two years. If we split and sell the property on the same day, are we still liable for the capital gains on any portion of the sale? When we purchased the property, it was all deeded together then as well if that makes a difference. My other option is to sell the property to my investment property LLC and then split it from there with a back-to-back same day sale, but I'm not even sure if I can do that since I have a mortgage on the property that will need to be paid off and I don't have the available cash to pay it off. Any suggestions would be appreciated! Thanks in advance!