Photo management question

My wife takes tens of thousands of photos every year, and so we use a Synology to back them up with a USB WD Passport and Hyper Backup as a safeguard. We'd use a cloud service but it's simply too expensive for the amount of capacity we'd need.

She would like an additional copy of her images on another WD Passport that she can carry with her, to offload images from her laptop when traveling, and just as a faster way to access them than over our home WiFi when at home.

So, I'd like to make a copy of her photos from the NAS to the Passport, but every now and then sync the NAS with any additions, modifications or deletions she's made on her portable copy.

Is there a good folder sync tool for this built into the Synology? Thank you!