Munnelly and Lavelle Binghamstown/Belmullet

You may already be aware of them, but there are records for what appears to be that family in the Famly Search database [https://www.familysearch.org].  If you create a (free) account there, you can find Anthony under ID number KHDF-PWR, and can access the records for the others easily through his record, as you will see.

The site automatically locates other potentially relevant records, and right now is offering 1901 and 1911 census records for what appears to be the same family, with Bridget and John still living with the parents in 1901, and just John in 1911 (with John's wife and children).

In each record, you can see the screen names of those who have created or modified the record, and can send them private messages.  The same person appears to have input all of the information, so you might be able to get more info by contacting her (and perhaps also locate some relatives that way).

As for the marriage, it should be possible to find it if took place in Belmullet, since the online parish records go back to 1857 for marriages (which should be early enough, given the birth years of the children).  Those records can be accessed here:  https://registers.nli.ie/parishes/0742

However, Family Search also shows a Mary Munelly who was born in 1856 in Castlebar, and lists her parents and siblings.  That seems a bit late if her first child was born in the late 1860's, but there may have been an error in what was entered as her birth year (no source is cited in the record).  You can see that record offered as a potential duplicate record for Mary when you are in her record (the one linked to Anthony).  If that proves to be the same Mary, then the wedding may have taken place in Castlebar (weddings usually took place in the bride's parish), and the records for Castlebar cover the entire likely time period, and are available here: https://registers.nli.ie/parishes/1039

The records you have indicate that the family was living in the townland of Glencastle (in the civil parish of Kilcommon) when the first child was born.  You can find more info about that townland here:  https://www.townlands.ie/mayo/erris/kilcommon/glencastle/glencastle/

It's hard to tell the name of the townland where the other children were born, since it appears to be abbreviated, but there's a list of all of the townlands in Kilcommon civil parish here:  https://www.townlands.ie/mayo/kilcommon3/

In case you're interested, the surname Lavelle comes from the Irish surname Ó Maolfhábhail, from a word meaning "movement", and it originated in North Connacht, though it is also found in Donegal.  It was originally anglicized as Mulfaal, and sometimes as Melville.  Munnelly is also a Mayo surname by origin, and is one of the anglicized forms of the Irish surname Ó Maonghaile, from a word menaing "worth" or "valor".  Other anglicized forms are Monnelly, Mannelly, Manley, .Monagle, O'Monnilea, and Monylla (the last two being older forms).