i feel like adarsh was like and probably still is the quintessential good older brother. he listens to his elders but isn't blinded by their old school thinking. he does subscribe to a lot of their teachings (studying commerce instead of engineering, having an arranged marriage, treating his wife as less superior than him, etc.) but at the same time, has also shown a tendency to be lenient and open-minded (giving Lucky keys to go outside, wanting his wife's opinion, etc.). He definitely loves his brothers and they love him too. and he probably tried to protect them when they got in trouble.
i feel like sanskaar was the naughty brother who liked doing mischief. like deepika (hope i can call you that) said about laksh's mother describing sanskaar as the life of the house. he was probably very fun loving and thus got into conflict with maheshwari's old school thinking and strict traditional behaviour. that's why he did something bad? (out of wedlock pregnancy -- something that big and that kind of bad i'm guessing) As for his brothers, they probably really liked him and had fun with him. I think Laksh probably really looked up to him and liked him as kids always gravitate toward fun-loving people. and in turn, sanskar himself was perhaps quite supportive of lucky as well.
laksh -- i feel like he was deeply influenced by sanskaar initially, in adopting a carefree and fun lifestyle under the guise of lucky. he is the baby of the family so probably got away with some and was influenced by the older brothers more as well. sanskaar helped him with being lucky and adarsh helped him maintain lucky.