Pondering Pear Pollination Problem

I realised that the oldest pear tree we have, planted around 10 years ago, STILL has never fruited. About time to do some research. The problem...pollination problems. The pear tree in question is a Moonglow variety. It needs a couple more similar pear trees within close proximity to fruit. We do have two additional pear trees, they're not in close proximity though and one tree we don't know which variety of pear it is. If it's an Asian then it may not pollinate the Moonglow tree. The third tree was added last year and it's a Kieffer pear. This could be a good pollinator for the Moonglow Pear  but it's quite far away and pretty young. The Kieffer can be somewhat self pollinating (would be more so down south) and has one pear growing on it! We didn't set out to have non pollinated pear trees but two additional pear trees that were added in past years both failed to thrive and eventually died. Our mission now is to purchase and plant at least one more good sized, healthy, European pear tree in close proximity to the Moonglow and probably add another close to the Kieffer pear tree.

Moonglow Pear 10-ish years old

Trunk diameter 5" plus

Kieffer pear tree

One pear!

KitKat supervises.

Pear trees to far apart?