ER Contributions vs Deductibility

[SwimmingInBowelsOfERISA]

Example: 4 family members own a s corp biz (mom, dad and adult children), no other EEs. They currently pay the same salaries for all 4 (~30k/yr). They sold the assets of the business (~1.5M) early this year but retain the entity, which is now flush with cash. Just over 1M is not basis so subject to form 1231 cap gains.In order to minimize cap gains, we are considering a combination of 1) reallocation of equity (gifting some by parents to children using small part of lifetime gift exemption before eoy to keep cap gain liability at 15% (they should have gifted the equity before the sale but besides the point), and 2) starting a k/ps/cb plan to reduce AGI from 1120s, but naturally considering adjusting comp before eoy to get to funding levels for the ps/cb that make sense. Since the income of the business was minimal (sold early in the year), they will show significant loss of income in the business due to ER contributions to owners for ps/cb plan. However, they own several other businesses (no EEs other than the same owners) that will pay a management fee to the original co or the original may just become a holding co for the rest, to be determined, but income will flow into the entity after this year.

My question is:

1) is there a limit to deductibility for ps/cb plans for an all owner/family relation company w no other EEs?

2) can losses due to contributions be carried forward like other corporate losses?

Thx!