Beretta has owned portions of many of its rival gun companies: FN, Benelli, Franchi, etc. When GIAT put FN on the market, it decided to buy out Beretta's interest in FN (I've heard 25%) in order to make the deal less complicated. It would appear that Beretta used this windfall to finally buy out Benelli.
As for the Beretta 1201FP3/Benelli M1 Super 90 connection, my understanding is that Benelli provides the bolts and certain other parts for the 1201 while Beretta constructs the rest. The contour of the 1201's receiver and barrel vary from the Benelli slightly, so aftermarket Benelli parts like the Sidesaddle will take a bit of fitting. The Laser Products flashlight forearm is reportedly a poor fit as well. Aftermarket bolt handles fit as would be expected. The 1201's magazine tube cannot be extended, but all but current production models have a 6rd magazine already. I'd like to try the new extended safeties on the market, but I haven't gotten around to it.
