Flexible Discretionary Match - allocation groups and plan document

Client restated for Cycle 3 in 2022 and after much discussion decided on the Flexible Discretionary Match primarily because they wanted 2 different match allocation groups.  They are matching 100% of 2.5% for NHCEs and 100% of 1% for HCEs on a pay period basis.   My understanding is the first notice is required for the 2023 plan year and within 60 days of making the final match contribution so likely in March 2024.

First question - is the allocation groups they chose - HCE and NHCE, not job related necessarily.   We can change that to define positions that are HCE if we have to such as CEO, COO, CFO, HR Director, etc.  Do you think HCE and NHCE is ok?   There are no working owners and so it is just prior year comp based.

Secondly - under flexible match, must the match allocation groups be mentioned in the plan adoption agreement?  Or can that be left unmentioned since this is a discretionary match and the notice isn't due until after the end of the year?

This is the only flexible discretionary match client we have - fortunately.

Thank you 

Tom