How to merge a URL with a photo in MS Publisher?

I have a client who creates a Publisher document using a merge. The info includes five lines of text data and a photo. There is an associated URL for every photo (not the same URL — a different link for each) — we can’t figure out how to assign the URL to each photo (so we’re having to manually put it in for every one after the rest of the data has been merged — and there are thousands of photos).

Anyone know a way to do this?

TIA —
Julia