How to move a big branches to a new base?

Hi,

I have a branch that have about 10 descendent branches. Now I would
like to move this branch, and all the descendent branches, to a new
base, and I might need to do so quiet frequently before I merge it to
master branch.

My "dirty" way is to rebase step by step, it takes about 15-20
rebases, but the branches is somehow complicated, and this seems
error-prone to me.

Is there a more clean way to do so?

Thanks in advance.

Best Regards,
Mac Lin