Replace your mothers every 4 or 5 months - keep them young and vigorous.
Defoliating, removing fan leaves, chopping branches that won't be needed .... all are OK, the mother is there for a reason ... producing clones, not developing the perfect shape, structure or leaf distribution - it is there to produce clones so butcher it if needed.
If it is producing more than you need, prune away the excess and throw the clippings in the next batch of cannabutter.
If it is growing too quickly, selective defoliation slows down growth.
Far too many growing points, prune low down and let it regrow.
Hack, chop and mutilate - and replace frequently.