Two Safe Harbor plans and 410(b)

Law firm wants two 401(k) plans, one for equity partners and non-attorney staff, the other for associate attorneys, to avoid top heavy minimums for associates.

They also want to offer a SH match in the partner plan (TH for associates is still an issue as they also expect to do PS contributions).   I've advised that the associate plan will also need SH match as the associate plan needs to aggregate with the partner plan for its CODA to pass coverage since most associates are HCEs and cannot aggregate SH and non-SH CODAs.

So, can the partner plan offer the SH match to all participants, HCEs and NHCEs alike, while the associate plan offers SH match just to NHCE associates should there be any?   Seems like this should work. 

Is there a top 20% election in effect and if so even with that there are still associate HCEs?  

Top 20 is a good thought, thanks.   It's a new firm that started this year and frankly the partners' K-1 earnings may be less than some of the associates W-2s this first year.  Won't know this til next year when the tax work is done, but need to get the SH provisions nailed down now.   

How are there any non-owners who are HCEs in the first year?

No, just 3 partners are HCEs in 2017.  But there will be  HCE associates in 2018.  

Seems to me it should work, too.