Queriesfor HUF

I'm my HUF Karta. I've HUF Savings Bank account as well as HUF PAN card. Also, I've been filling ITR for HUF.
During almost 20 years of formation of my HUF, my son and daughter got married. How do I change (Add/Delete) member's (co-parsners) names in HUF ?? After my demise, if I'm survived by my wife, does she automatically become Karta, and continue with HUF? What formalities are needed to be carried out in case of both my queries above ?