MEP - Testing question - 1st year with NHCE in participating employer

We have a multiple employer plan with two companies, Company A and Company B.    Company B is a participating employer in the Plan sponsored by Company A and the document says ADP/ACP testing is using prior year method.

Company B came into existence in 2022, with only one employee who was classified as an HCE.    In 2023, Company now has 2 employees, the one HCE and now one NHCE who transferred over from Company A and was previously eligible under Company A.    The document counts past service between the two Companies.

What is the prior year deferral percentage for the NHCE when testing for 2023 in Company B?  0% or 3% since it is the first year Company B has NHCE employees?    Can Company B elect to change to current year testing or must both Company A and B move to current year testing?

I would think (and I will freely admit I haven't done MEPs in years) that if the NHCE testing population consisted of 0 NHCEs for 2022 that 2023's ADP prior-year test will automatically pass.