I found Ursula's baptismal record and then her father's marriage record at Seyboldsdorf (thank you Danny) and it appears the name is Sietl (also written Sÿetl). The information regarding bride and groom is "stuffed" into the designated box and very difficult to read. If you care to give it a try it is located at https://data.matricula-online.eu/en/deutschland/regensburg/seyboldsdorf/Seyboldsdorf001/?pg=94 (30Jan1653 on left page).
Thanks to both of you. You are a great help !