How to add watermark to the cover in batches?

[ohrenkino]

Pictures are added "as is". So the picture would already have to have the watermark.
Here is a thread about pictures that should be overlayed with something else - which is not possible:

Overlay a cover image with already existing one

I am new to this community, but am using this software long days back, I am so impressed by this tag editing software, just wanna share some ideas. What if we can add a small cover image, like watermark and stuff that overlaps already existing cover image,. ? May be we can position the extra cover image by using mouse or by inputting padding like values.