They combined to form only a company of the 10th Missouri.

Ainsworth files Nat’l Archives -
Priest Missouri regiment-March and April 62, Priest was Lt Col 5 Infy bn MSG.
5/62 Colonel of small Bn.
8/62 Col of 2nd cavalry Regt 6 Div MSG which enters C.S.A. service 9/1/62
11/10/62 remnant consolidated with Winston’s Mo Regt remnant to form Co A and B of 10th Mo Infy.

Once again, I wish I had definitive answers for you, but the few sources on Priest [and Winston] are all over the place, so a conclusion must be left to the individual researcher..