H4 transfer with H1B transfer? - Stamping questions

H1B will soon be transferring to a new company and since h4 and h4EAD are still good with validity (Aug 2025), we are thinking not to apply for H4 and EAD transfer along with H1 transfer. In this case, H1B and H4 validity dates are going to be different. We are planning to travel to India later this year and since our previously stamped visas are expired, we’ll have to go for stamping. Will H4 have to use the new H1 i797 petition for stamping or current H4 I797 copy with Aug 2025 validity? and what validity date will H4 get on the visa stamping?

H4 visa validity will be same as H1B validity.

Thank you so much Anil. Another question: In this situation, how early can we file H4 EAD with new validity? does it have to be filed only 180 days before the current EAD expires or anytime after H4 visa is stamped?