Use your DNA test to compare with other testers too? Especially those with Limerick connections? Wikitree (free) has millions of records / trees and ofte with DNA test notices for testers on the major websites but use Gedmatch too (free)
At the very least perform a Leeds Method on your best known matches to make clusters of your top DNA matches. This has two major effects, each group is a part of your tree and any new matches can easily be grouped into known areas of your tree. By examining the matches for a tree and or origins you can work away at useful threads of research rather than a mass of 'useless' DNA data.
I would add that looking at major DNA matches will not find your Ponsonby? Anyone of that name in Ireland will have only a small match with you after 200 years, so even if you get a modern day Limerick match it means you are not necessarily going to "prove" it is a Ponsonby match and not another Irish match? Using y-DNA testing could identify a Ponsonby line but if you look at the people with this type of research, not many people have y-dna matches. My own case has proven that there are at least 15 different male haplogroups for my surname. Whilst there are manu 'non-paternal' events, adoption is one and was common there was also a system of inheritance that did not involve the eldest son.
Given the Ponsonby name it is possible they were not catholic by religion and so the protestant church records are still being transcribed. Post a message in the Limerick board to see what non-catholic records might be available. Someone else has probably had to do similar, so it is worth a shot?
