Does widow and child inherit full 25% share or partial?

A property that is in the name of 2 brothers, a sister, their mother with an equal split of 25% each. With only brother 1 being the breadwinner / caretaker. The building also has loan which was being paid by brother 1. Brother 1 passes away, leaving behind a wife and toddler kid. Question is from the 25% ownership share of Brother 1.. As class 1 legal heir do the widow and daughter get 66% of the 25% share as mother who is also co owner of the property but also falls in the class 1 category of legal heirs.... or the widow and child entitled to the complete 25% as the mother already has 25% ownership.