Crediting deals
Who gets credit for a deal, and what that deal pays them, are two different questions. Keeping them apart is the reason unusual comp plans fit.
Two questions, not one
Most commission tools fuse crediting and commissioning: a deal belongs to a rep, and the rep's plan pays on it. That works until an SDR gets 20% of the deal they sourced, or a manager earns an override on their team, or two reps split a territory account.
Here they are separate. Credit rules decide who is attached to a deal and in what share. Plans decide what those shares are worth. Nearly every "your tool cannot model our plan" complaint traces back to a product that fused them.
A credit rule
A rule has a filter saying which deals it applies to, and one or more splits saying who gets what share. Shares must sum to exactly 1.
The simplest useful rule is the one most companies need: the deal owner gets everything. Its filter is true and its single split targets deal.owner_external_id, which resolves against the identifier on each payee.
Priority
Rules are tried in priority order and the first matching rule wins. Put your specific rules above your catch-all, or the catch-all will claim everything.
A deal nobody is credited for is reported, never dropped
If no rule matches a deal, or a rule resolves to a person who does not exist, the deal is parked and named, with the reason. It is not silently skipped. A deal that nobody was paid for looks exactly like a correct month until somebody notices the revenue does not tie out.
The same is true at the other end: a deal credited to a real person on a real plan, where no component in that plan pays on that deal type, is reported as credited-but-unpaid. Both are asked about again at approval, so neither can be waved through by whoever happened not to be looking when the run finished.