father of Heinrich, Poppo and Egino

He might have been Poppo I, Graf von Grabfeld & Tullifeld.

There appears to be a large chronological gap between Poppo [I] and the three brothers Heinrich, Poppo and Egino. It appears wise therefore not to assume that the latter were sons of the former without further proof, although if they were not his sons no indication has been found to identify their father. Jackman suggests that he was Christian [I] Graf im Grabfeld, his son Christian [II] therefore being another brother[55]. However, if this is correct, it is surprising that the name Christian is not found among the descendants of the three brothers. Presumably Jackman bases this speculation on the common reference to Grabfeld. However, as noted above, there were several different families of counts who held countships in Grabfeld at the same time and it is not certain that they were all related to each other.

http://fmg.ac/Projects/MedLands/FRANCONIA.htm#Heinrichdied886A