Herbert Oppenheim was nephew to my G G Grandmother, Emma Oppenheim, (who became a Kohler upon marriage). Her father was Henry Oppenheim.
Herbert's father, the son of Henry senior, was also called Henry.
I have them all detailed on my family tree on Ancestry.com and would be delighted to email te relevant link to you so you can see it all for yourself, which ill make it much clearer than trying to explain it! So far, sorry, I have no date of death for Herbert.
I would love to know if the Oppenheim family are/were Jewish... perhaps you might have an idea?