Question about ERTC

Hi, I work for an owner that owns 2 businesses. I am in the process of going back and helping him amend his 941's to claim the ERTC. My question:

1. When filing a 941-x for two businesses that qualify based on aggregation, is there anything different we need to do versus filing a single 941-x.

2. One of the businesses is an S-Corp, can the owner claim his own wages?

Thank you for your help everyone.