PS starts with the part “pati + icca” (getting attached to an arammana with like or dislike, until namarupa are established with vinnana paccaya namarupa), then it goes on with “sama + uppāda” (creating new bhava/existence, from namarupa paccaya salayatana). The step namarupa paccaya salayatana starts again with a similar object (arammana), hence sama uppada happens if not controlled with panna/sati etc.
Namarupa are in the middle and contain objects of attachment. Whenever we contact similar objects those namarupa show the way how we like to “see” the object. Thus we get attached and add more fuel (san).