I always do charitable things like digging wells, building mosques, reciting the entire Quran, Haj and Umrah.…

Answer

In the name of Allah, if you mean that your cousin is to get rewards out of what you do, this would be a good deed for you. We pray to Allah that it is accepted and grant your cousin more and more rewards. If you mean to get blessed with by putting her name, it is also permissible. Allah is the Guide and Knowing.