How do the Mythic Lockouts work in World of Warcraft with cross realm progression?
Solution 1:
No, you can't do that.
If you started a raid with a group you have exactly that ID and cannot join another group with the same bosses (or any other number greater than 0) on a different lockout ID.
Your group can even kill bosses without you and you'll find them dead if you go there at a later time.
If you're quick enough or your first group didn't continue their ID you can do so with a new group. However, they all have to have no ID on Uldir Mythic or they will face your problem again.