If you enable attachments to the signs table then the photos are automatically attached to the sign record in the sign table. You do not have to create an additional relationship. The only issue with storing photos in the table is that in a web map, you can only view them by first clicking on the point (pole) then viewing a related record, then viewing the photo. I have a similar set up for sign poles and multiple sign panels in a related table. But I chose to enable the photos on the poles so I could view all photos quickly instead of viewing a related record and then a photo. Not sure if my answer helps.
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