My client, lets say A, filed as Single for 2019 tax. For 2020 tax she is filing Head of Household claiming her

grand daughter, B. 

For 2019 tax the child, B, was claimed by the mother, C, and the mother (C) received both $500 in 2020 and the $600 in January 2021 for the child (B).

What should I enter on the Rebate Recovery Worksheet Line 6 and on Line 9?

For Line 6 if I enter $500 and on Line 9 if I enter $600 then my client gets recovery of $1100 added to her refund. 

But if I enter '0' on both lines then my client does not get the additional $1100 which actually she should not get as the mother, (C) had already received $1100 for the child. But I am not sure if this will affect her being Head of Household.

Any help is appreciated.

I am wondering