What would you do to prevent the elder sibling from feeling left out upon the arrival of newborn and mummy is doing confinement?

Have his cousins and other family come visit (which usually happens anyway after a baby is born) so the older child will not feel alone or left out when you're busy recovering or with the new baby. When my baby brother was born, I was lucky to not feel that way because I was raised by my grandparents along with other cousins. So whenever a new baby arrived, we all knew that we were getting a new playmate.