Dual Time Signatures

See https://musescore.org/en/handbook/time-signature#local-time-signatures

Here is my recommendation on local time signatures based upon my personal experience.

If you are going to use a local time signature I will warn you that copy and paste almost ceases to exist as an editing option because MS thinks that the entire local time signature section is a tuplet, and you cannot copy or paste a partial tuplet. I would input everything possible without the local time signature that I can, then enter the local time signature where needed. If it is only for part of the song, then you can leave the section for local time signature empty without entering the local time signature. Enter the main time signature where it changes back THEN enter the section with the local time signature starting with the time signature. This should make your input session easier. Changing the entire score to a new time signature from a section with mixed time signatures is problematic, I wouldn't try it.