Now that we have been informed of DB's forceful entry into Mathur Mansion(MM) and Mallu's backdoor entry into the same place, let's analyze the pros and the cons of them together in MM.DB's entry: Cons 
- Will increase noise pollution in the otherwise calm and quiet MM.
- BB may have a relapse of Alzhiemers
- HK may threaten to quit due to usage of unparliamentary language such as Abbe Manoos etc.

- Neighbours may react to paan stains in the locality
Mallu's entry: Cons
- She will monopolize Ashu
- She will try to plot against Nidhi
The list is too long and depressing so will stop here but but...
the aim is not get depressed so let's look at the pros of having DB in the house with Mallu.
1. DB and Mallu will share a room.
Otherwise our Ashu would have asked Nidhi in the same room as Mallu just in case she needs help in the night.

Worse Ashu would have slept in the room (on the floor)

Or Mallu would have come disturbing them in the night.
Now one word from Mallu inthe night DB will sing her a lullaby she'll never forget.
2
. Mallu tries to play dirty DB will take her to the cleaners. 
Mallu tries to go anywhere near Ashu DB will be in the middle screeching into her ears. Mallu will not hear for the next barah saal.

3. DB will take Mallu (BB and HK too)to the temple

every evening giving Ashu and Nidhi time alone. .

4. DB knows Sue, she will bull-doze Sue into taking care of her sister-in-law by giving her long bashans.
5. One tear from Nidhi and DB

will tear Ashu. So Ashu beware
6. Ashu has anyway promised to woo DB.
The route to DB's heart is via romancing Nidhi.
So all is well with DB's entry into MM. and will pave the way for Mallu's exit.