H4 AND EAD(I 90 valid) -H1B(New-2021) - To H4 conversion

[samuel1]

Hi All,
Could you please help us with our situation,
My spouse is on H4 and H4EAD(valid till Oct 2022) and working with Employer A
She got selected in 2021 H1B visa from Employer A and B
Employer B H1b approved in Jan 2021 and Employer A H1B in Feb2021
Employer A- Attorney said they filed H1B with out COS but we got H1B with I-90
Employer B - Filled with COS, but she did not joined that company and still working with Employer A.
Employer A asked us to file H4 COS to avoid confusion and we can work with them.

Now she got regular position with Employer C and they hired based on H4 information .
can my spouse join and work C company with pending H4 and valid - H4EAD(old one).

Thanks 

Sam