On Kidushin 47B Rav Pappa says that "When one sells a note to another he must write a clause in the Shtar 'acquire it together with all its obligations (or 'liens')'".

If Rav Pappa agree with the dictum of Shmuel, he should have added to that clause something like: "And if I waive part of or all of any of the loan(s) I will personally reimburse you and all my possesssions are guartantors of this Deed of sale."

Since Rav Pappa did not include such a clause it seems that Rav Pappa did not accept Shmuels ruling on the rigth of the seller to waive the loan - On Daf 48A Rashi explains that Rabanan (who disagree with Rabbi Meir) agree with Shmuel and with Rav Pappa - So how do we explain Rabanan? Why don't Rabanan recommend - or insist on - such a clause?

Or are we to say that the ruling of Rav Pappa is to validate the sale, and without the clause 'acquire it together with all its obligations (or 'liens')' the sale is INVALID, and if the seller waives repayment he must reimburse the buyer; if however, the clause was used - the buyer looses his money?

If that is so - then Rav Pappa's ruling the this clause must be used is directed against the buyer - so why should the buyer insert this clause? On the contrary - he should surely make sure that NO such clause is used, so that if he can't collect the debts he purchased - he can return to the seller and cancel the sale of the debts!