Well done, vm. Thank you. From the citation Tank gives I am thinking that “Popkiss” might be a “nurse name” for “Hopkins.” I had a grand aunt called Lalla. Her actual name was Ellen, but when my father was a toddler he could not pronounce that and said “lalla” instead. So she remained for the rest of her life. It is a little harder to understand such developments in surnames.
As described in some old texts, a nurse name is a contraction or an affectionate nickname. One example I found was HUBE, a "nurse name" for HUBERT. Other examples weren't shortened versions of one's given name but as terms of endearment, such as LITTLE ANGEL or DEAR ONE.