advise needed

is she still with chicks or back laying?
can you do a set up when all the chooks can see one another?
she might not be accepted until she is laying again.

If it is two hens sorting out the pecking order i would let them get on with it !
I would only separate if one hen was getting a beating from several others.
Best to reintroduce when there is another distraction (food) rather than have one of the top hens come out of the coop to find an old rival in the pecking order.

Broodies fighting are not your normal pecking order fights, they will fight to the death in my opinion.

How old are the chicks now?  I have taken some broodies away from their chicks early when I think their health is suffering, usually when the chicks are around 8 weeks old.  If you can let the adult birds free range together and have plenty of feeders and drinkers for them that might help.  You will probably find the broody will pace up and down the fencing nearest to her chicks.  The bond is really strong so you might be better taking her away from the chicks each day so she can have some layers pellets made in to a porridge with boiled water.  This will build her back up and give her the right nutrients is she is laying again.  If you keep her away from the chicks for longer each day you will be able to assess when she is ready to join the main flock again.