Account for upgrade is different to account in phone settings
NRaf,

Chances are the friend downloaded those apps under his/her Apple ID. Thats why it's prompting that Apple ID username/password.

Simply delete those apps and reinstall them under your Dads account and everything will be fine. 

If these are Apps that your friend has paid for but your dad has not and thats why the friend downloaded them to his device so your dad wouldn't have to pay for them, then thats a different issue. look into family sharing and see whats going on there from both parties.