Dear Brother, I intended to sacrifice for Eid ul Adha and sent money back home. They are sacrificing a cow and I decided to be a part of it so I sent my share of money (1/7th) since seven people can sacrifice one cow. Is it permissible for me to cut hair during the dhul haj since i am not doing the sacrifice by myself. instead on my behalf it will be done since i sent money to a friend who will put it for a cow in which other six people also have a part?
Bismillahir Rahmaanir Raheem
Al Jawaab Billahit-Tawfeeq
It is Mustahab (desirable) to not cut hair and nails for those people who are sacrificing. Nonetheless, it is still permissible for them to cut hair and nails. They will not be sinful at all for cutting and will miss out on the reward of that Mustahab act.
Since you own a share (1/7th), sacrificing on your behalf means your own sacrifice. So, in the case you mentioned above, it is Mustahab for you and the other six people who have a share in that cow to not cut their hairs and nails. However, it is also permissible for any or all of you to cut their hairs and nails.