u/Electrical_Bag_5315

Hello. I (18M) want to buy Birkenstock Gizeh sandals for my mom (49F) as a Mother's day gift. My mom actually loves flip flops but she doesn't own any Birkenstock sandals so I thought Gizeh sandals would be a nice gift for her. How comfortable are Gizeh sandals compared to flip flops? And I don't know my mom's shoe size. I think I can look at her flip flops' size. Should I buy her the same size as her flip flops? Would they fit to all foot shapes? Thanks.

I (18M) bought my mom (49F) thong sandals for her birthday two weeks ago. Since the day she got them, my mom started wearing them. My mom wears a size 35 EU (5US) for her flip flops so I bought her the same size for her thong sandals. However, we were both studying in my university's library last weekend (my mom is a high school teacher and she was preparing her classes) My mom kept removing her sandals when she was seated and played a lot with them. Is it possible I bought her the wrong size sandals? What should I do? Thanks.