In that case opt for consular processing. New employer when they file H1B have them check under I-129 Q.4 a Notify the office. By following this approach you can have H1B approved & attend consular interview get H1B stamp & re-enter USA based on new employer's H-1B
Effective 01/01/2021 USCIS/DOS is no more allowing to file I-485's based on date of filing. It has to be based on Final Action Date. I believe this might help you in your understanding to file I-485 for your spouse should the need be. This is in regards with employment based I-485 filing.
OK. So if I-539 was timely filed, he or she will be under period of authorized stay until it is adjudicated from US attorney general . I believe you are OK to file I-485 without having the need of invoking 245K
Try to get birth certificate under correct name from local authority if not non-availability certificate along with 2 affidavits 1 from your dad's side and another from your mom side & include nickname in I-485 under also known as