For a copy of a birth certificate, go to City (or Town or whatever) Hall. For a copy of a Baptismal Certificate, contact the surviving parish office or, if in doubt, contact the diocesan chancery and ask.
Call the new parish that was formed when the closed parish merged. If the records are not there then they will refer you to the diocese.
If you can’t find the new parish, don’t know which parish merged with which and what new parishes were formed, then you will have to call the diocese to find out. Sometimes the diocese website will have a history page which will tell you about parish mergers. The website will probably have a page about sacramental records. That is a good place to start.
I went through this with a parish that closed in Michigan. The records were moved to the new parish, and then moved to the diocese of Lansing. It took a while to track everything down.
I was in a similar situation. I called the Archdiocese. They actually told me the old church was not completely defunct but that there was no one in the office there except on Tue’s and Thur’s. It seemed that the Priest also shepherded two other small parishes nearby.
Even if they are completely closed the Diocese should have that info or can tell you where to find it.
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