עיין בהקדמת שו"ת 'להורות נתן' שמביא י"א שהוא הי' חתן היעב"ץ בן הגאון החכם צבי, וכך מובא בקונטרס 'יחוס משפחת שיף' שי"ל בויען שנת תשי"א

Elisha Koppel states otherwise:

In the Sefer כתנות אור by the Panim Merios it is written in the Haskomah as follows that R binyomin Asch was the eldest son of The Panim meirot. The Ponim Meirot was born in 1670 so it can be assumed that R Binyomin Asch was born latest in the early 1690's. While the Yaavetz was born in 1697 so it is unlikely that he married his daughter.

What makes it impossible is that the Paniim Meirot quotes in his responsa that he was in Amsterdam for the wedding of his youngest child R Yitzchok to the daughter of the Chacham tzvi and he speaks about the family. He doesnt mention at all that he was already related to teh family as his eldst child married R yaacov Emdens daughter.

None of the historians bring this down and I found this at only one source which most probably mixed it up with his brother R Yizchok as they did not quote R Yitzchok being married to the chacham Tzvis gaughter