Kansas Karla -
Your mind is trying to run everything together...like Judy says, Sit back and concentrate on these transactions one by one.
The Uncle is not a related party, according to IRS definition. That is fortunate as it avoids other problems. Simply record a Notes Payable to the partnership for $100,000. At the time of this transaction, the amortization is irrelevant. So each partner then walks away with $50,000 each? Set up a "Loans to Partners" account (preferably 2 accts, one for each partner) for $50,000 each. At this point, neither partner has to pay tax because it is a loan.
Going down the road, it becomes more complicated if these partners think the loan can sit on the books forever and them NEVER pay tax. This phenomenon is common and has consequences. There is a matter of imputed interest which affects the partners, and there can always be the IRS waiting in the wings to reclassify the loan as income if there are no characteristics that qualify as a loan. A loan has to be paid back, and if the borrower doesn't pay it back there are consequences.
If you really want problems, just think of what happens if one partner pays back the loan and the other doesn't? Will this "uncle" stay uninvolved? If they can't pay the loan back, what makes anyone think they will be able to pay uncle back? There are personal problems with this whether there are problems in the books or not.
Are you a preparer, or a bookkeeper, or just a friend trying to "help out"?