The way laws are broken left, right and centre in this serial, I would'nt be surprised if Milind did get SM by crooked ways. I would have put him on a pedestal. But after his bribing Neev's employee to get the contract and indulging in arson, all in the name of revenge, I would'nt be surprised if this property was also acquired through crooked means (not that Milind did'nt have the money to buy it but just so that he can get back at Ayesha). After all this is also part of his revenge plan.
Yes, Milind has discharged his duties to the people of the house. The people of the house also respect and take care of him well. What has Prachi not tolerated for him? PL has been more than a mother to him. For the first time in his life he got the love of an entire family. And they accept him as the owner of the house because legally he is. And if he was not the onwer, it would have been that revengeful Ayesha, who would have definitely thrown them out, which she tried to do. Yes, they are grateful to Milind and they have to be. Who put them in this position in the first place? If Prachi had not given away the property to Ayesha in the name of sacrifice, all this would not have happened in the first place. So yes, since Prachi was the root cause of this, I guess it is some poetic justice she gets thrown out of the house.