The question here may be based on some assumptions, relating the culture of the distant past to that of today. the simple-seeming question
What happened when the burial holes where full and no more room was in
Is probably answered by a simple-seeming answer: They buried them somewhere else.
The issue is that we assume the burials might be ...
You've already mentioned Blombos cave. One early upper paleolithic (European) example would be the Grotte Chauvet (~36kyBP). Ochre is habitually (sic ;-)) used (an found), e.g. in the middle and late upper paleolithic cave and wall paintings (25kyBP and later).
Use of red ochre (and hematite) is documented in the middle stone age (Africa) and middle ...