For software that interfaces with Bitcoin Core via RPC, it can be useful to know whether the fRelayTxes flag is set. It could be added to `getnetworkinfo`.

{
                
                
                
                
                if (!setConflictsParents.count(tx.vin[j].prevout.hash))
                {
                    
                    
                    
                    if (pool.mapTx.find(tx.vin[j].prevout.hash) != pool.mapTx.end())
                        return state.DoS(0, false,
                                         REJECT_NONSTANDARD, "replacement-adds-unconfirmed", false,
                                         strprintf("replacement %s adds unconfirmed input, idx %d",
                                                  hash.ToString(), j));
                }
            }
            
            
            
            if (nModifiedFees < nConflictingFees)
            {
                return state.DoS(0, false,
                                 REJECT_INSUFFICIENTFEE, "insufficient fee", false,
                                 strprintf("rejecting replacement %s, less fees than conflicting txs; %s < %s",
                                          hash.ToString(), FormatMoney(nModifiedFees), FormatMoney(nConflictingFees)));
            }
            
            
            CAmount nDeltaFees = nModifiedFees - nConflictingFees;