it seeems you traded yor 50% interest in one property to obtain you other partner's 50% interest in another property. the IRS position is that you sold the first property and bought the second. Sales price would be 1/2 the total Fair Market Value of the property you relinquished.
That becomes your bais in 1/2 the property you acquired. the basis would need to be allocated between land and building. and sdate acquired is the date of the trade.
by the way have you been filing partnership returns?
