Statutory recording of births & deaths in Ireland started in 1864, so you won’t find birth certificates for any of the Irish births you have given. Protestant marriages were recorded from 1845 so again this marriage is before that era. However English BDMs started in 1837 so you should be able to get a birth cert for John Mullin born Liverpool 1846 and a death cert for William Mullin to find out what that horrible disease was.
To trace the records of birth and marriage in Ireland, prior to the start of statutory records, you are largely reliant on church records and you really need to know the person’s religion, parish or townland.
You say that Wm Mullin was a Baptist Minister for a while. You could contact the Baptist church in Ireland to see if they can confirm that he was a Pastor with them, and the dates. They may also have some useful personal data on him eg age, parents names etc.
www.baptistireland.org/If he was a Baptist, I suppose that might be unhelpful to your research because Baptists don’t practice infant baptism, and so there probably won’t be a record of Matilda Jane and Maria being baptized (unless the mother brought them up in another religion, which seems unlikely, I would have thought).
The tradition in Ireland is to marry in the wife’s church. So Wm & Mary probably married in her church in Ballymoney. Patterson is a fairly common name in Co. Antrim. There are 1511 Patterson entries in the 1901 census, and 36 in Ballymoney. All of the Ballymoney entries were either Presbyterian or Reformed Presbyterian (sometimes known as Covenanters). It was about a 40:60 split with slightly more being Reformed Presbyterian. (That all the Pattersons were Presbyterian tells you that their ancestors almost certainly originally came from Scotland, probably sometime around 1606 onwards). The difference between Presbyterian and Reformed Presbyterian is a theological one. Google it if you want more information. However from a genealogists perspective it means you have 2 lots of church records to investigate, assuming the records have survived. Unfortunately there are many Presbyterian and Reformed Presbyterian churches around Ballymoney.
If you go to the Public Record Office for NI website you can see what records have survived, church by church. However you cannot search these records on line. You need to search in person. Some churches have declined to let their records be copied, in which case you need to contact the church direct. (The website tells you where these are).
www.proni.gov.uk/index/research_and_records_held/catalogues_guides_indexes_and_leaflets/online_guides_and_indexes.htmGriffiths Valuation (1847 – 1864) was a land valuation across Ireland and is a useful genealogical tool.
www.askaboutireland.ie/griffith-valuation/index.xmlThere is one entry for a Hugh Patterson in Co. Antrim. He lived at Garryduff, Ballymoney. You should not assume that this is Mary’s father based on this information alone. But in the absence of any other information, you might want to start your search using Presbyterian and Reformed Presbyterian church records in that area.
You should be aware that Irish records at the start of the 1800s were very sparse, and there is a strong possibility you will not be able to find Mary’s family.
I assume you have also explored possible sources such as family bibles, will, obituaries and gravestones, all of which might give clues as to where exactly Mary’s family lived.