Hello from Australia!

I am in need of assistance with my research of the FRANCIS family from St Enoder please. As I try to piece together this family, my hair grows greyer....
Recently, I decided it was time to follow my Francis connection and so began my research knowing only that Catherine FRANCIS married Richard MURLEN (various spellings) on the 27.7.1743 in St Enoder.

Not much to go on, but I have scoured the St Enoder Parish Records, as best I can from here, and this is what I have found in Baptisms 1718-1742:
12.1.1718 Margaret Francis dau of John
21.1.1720 James Francis son of Richard
8.9.1721 Elizabeth Francis dau of John
28.3.1722 Jacob Francis son of Jacob
20.11.1724 Katherine Francis dau of Jacob
28.8.1727 Thomas Francis son of Jacob
From other sources I know that my Catherine was born circa 1724, and so I think they are one and the same just replacing a "C" with a "K". Catherine died in St Enoder in 1804, as did her husband, Richard.
Question: are Richard, John and Jacob, as noted in the Baptismal Records siblings? Is it at all possible to learn anything about them and/or their parentage?

How do I establish a connection, if indeed there is one?
From a bleary-eyed Elsie