How do you handle a return where the 3rd stimulus was pd to the taxpayer for 1 child and herself and the second child was pd to her husband who she does not file with?

She is amidst a divorce from her husband and she only knows what she received and it was $2800 for her and 1 child. Both of her children live with her and have been since February 2020 when she separated from her husband. We filed MFJ in 2020 using her address because she was being nice to her husband as if he filed MFS he would of had to pay a lot in federal and state income tax and when they filed jointly they benefited and though they were separated and living apart they were still married.  IT took over 4 months for her to receive her refund. If she filed separately or HOH since she did not live with her husband for the last 10 months of 2020 she would of still received roughly the same refund amount. She was being very generous to her husband by filing jointly. In 2021 this is not the case as their divorce is still not final but she refuses to file with him. I do not want her taxes to be held up since she receives minimal support from him. It is messy but she is entitled to the full 3rd stimulus of $4200 (additl $1400) but she knows her husband already received it and did not share with her. I know she is entitled to it but it may become a hold up on the filing of her return. This is a bit messy for my liking.