In short, no (or I don't know it). Each transaction and contract has to pay the fee itself. You can only change the sendMode for transaction.

You can try to organise this. Some random ideas

• Use contract B as proxy for all transactions to contract A and B will add some TONCOINS for payment. Also the surplus can be returned by contract A to contract B.

• If contract A has any transaction with a small amount, then A will send the transaction to contract B (also attaching the payment body) to receive some TONCOINS. B will then send back the transaction with some amount and attached body data.