Although I love to help our fellow crewmwmbers, if I can get a revenue passenger on, then that's who goes. If I returned to the gate to let revs off then we can take that many revs on, but I would not remove someone already on who wants to stay on. I always work the weights and have told the gate we can take another person and if they say it's closed, I have told them to put the delay on me, because I have NEVER been questioned about a crew delay.
Once in FAT I had two seats left and a family of 6 who wanted to ride together and did not want to split up. We also had an FO and FA who wanted to JS to SFO. I told the gate to let our 2 on if the family was not going to take the seats. The gate said they could not put nonrev in front of passengers, I said fine send me 2 passengers, they said that the passengers didn't want to split up . . . I said fine send me the crew members, the gate said they could not put the non revs on before the paying customers, this conversation happened THREE times!
I said OK, I got out of the plane, walked into the terminal and went to the father of the group and introduced myself as the captain and that we had two seats, and would anyone from his family like to go now to SFO, he said no. I then pointed out our two crewmwmbers standing by the gate and asked him if he would have a problem with me filling those seats with my crewmembers, (of course he said no) I looked at the gate agent and said, "put those two on my airplane." So they did. But it was incredibly stupid to have to go through all of that to achieve some common sense.