Unfortunately, Lindog, we do not allow multi-clanning. If you did wish to join BFM and go through the recruitment process, you would have to leave any other Halo clans that you're in. That is your choice to leave another clan, and we wouldn't want to put you out from another community if you enjoyed it there.
In the past, we've realized it just doesn't work being in 2 halo clans at the same time, and it can create problems because of it. We enjoy playing with other guests from other clans, however the dual-clanning can easily create a rift if there were ever any issues that came up between the clans.
Ultimately, its your choice to make, and we would understand both ways... whichever decision you were to make