Encyclopedia of Rose Science states this is Elsie Melton x Elina. There are other Wambach roses in that book possibly not on HMF, but unfortunately I have access to very little without paying for the entire book.
I'm hoping someone has full access to that book to see if any were missed.
Her husband made one of the most beautiful HT roses I have ever seen then and even until now -- 'Catherine Marie', which is maybe named after her or another relative. Unfortunately, mine had a mosaic virus, like all other clones did. I culled it and it disappeared from the market. I regret not keeping it, but I also considered keeping it unethical.