I also have only Caleb Jr (1746 -1787) and Ebenezer (1752 - 1832) as children of Caleb (1723 - 1815) and Sarah Strong, but between Caleb Jr. and Ebenezer there was a lot of moving around between Northampton and New Marlborough and time to have at least one more that might not have been recorded anywhere. I have never seen anything in the general histories of the Berkshire Co. area that tie them together with an Abner Wright, but these folks ended up all over the map. Caleb Sr. may have been in Ontario Co, NY. & son Caleb Jr. ended up in Washington Co. NY while son Ebenezer ended up in Waybridge, VT. Lots of room for doubt here because there are lots of opportunities for lost/unrecorded events in this family's history.
I'll keep an eye out for Abner in my fumbling around.