You can tag any user on a photo directly via Onlypult.
After adding the photo press Edit in the media object adding field.
Hover over the image you need in the window that appears, and click the Man icon. Then choose the area on the image to tag a user, enter the relevant Instagram login in the search bar and press the Loupe icon. When the user is found, click the “+” icon.
You can delete a tag by clicking the Cross icon located on the right from the user’s name.