Inheritance tradition in “aristocrat” families is for estate and title go to oldest male, not first born. Selling was probably practical decision as maintaining those homes nearly impossible without regular large income. Not to mention “transfer” duties on the value of the property, and contents. A huge chunk likely required to be sold to pay the taxes, which may have driven decision to sell entire estate. If it’s true, that the brothers who had properties “bought for them”, could be that they had been given properties of the estate when father transferred it and they were replaced.
Not sure if transfers at death would have been more tax effective, as father is still alive this transfer could a been a costly unplanned mess.
No idea what provisions / conditions were for CM.
The sale was probably unavoidable given taxes due on transfer to son.