Linking Sojourners to Illegitimacy at Launceston, Cornwall in 1790s?

Question

I've traced some relatives to Cornwall in the late 1790s,1800's. If I'm right, the first children born to the couple in question were born illegitimately in St Thomas by Launceston, and the remainder born in St Stephens by Launceston. Looking at a map, would I be right in thinking that they are almost the same place? Just a couple of miles apart? After the first two children are born in St Stephens in 1796 and 1798, the people I presume are the parents are listed as being married in St Thomas, as sojourners, and the rest of the children are born there. I'm guessing the first two children may have been born out of wedlock, and the parents moved away slightly to marry, and had the remaining children thereafter. Would that be the possible meaning of sojourners?

The couple in question are Thomas Peardon (born 1796 St Thomas) and his wife Mary. Their first child Thomas was born in 1796 St Thomas, according to the census of 1841, 51, 61, 71. (I have also found a Thomas PARDON born to the parents Thomas and Mary in St Stephens in 1794 though). I have his sister Mary born in St Thomas in 1797 according to England Births and Christenings, 1538-1975. Then in England, Phillimore Marriage Registers, 1531-1913, I have the marriage of Thomas Peardon and Mary Jewell at St Stephens in 1801, listed as sojourners. They have already had a son Richard Peardon, born 1801 in St Stephens, according to England, Select Births and Christenings, 1538-1975, and then two more sons, William and Robert, in 1803 and 1806 in St Stephens. So did they have two children in St Thomas, move to St Stephens to get married and then have the remaining children?

Answer 1

As commented by @HarryVervet:

I think the sojourner part of your question is answered here: Meaning of term Sojourner on 1794 Marriage Record at Marystow (Devon) for John Creber?

Consequently, I'll address this part of your question (and leave the likelihood of illegitimacy in the scenario that you cite to another answerer):

Looking at a map, would I be right in thinking that [St Thomas by Launceston, and St Stephens by Launceston] are almost the same place? Just a couple of miles apart?

Yes, the two parishes are adjacent as you can see in the map on the Cornwall Online Parish Clerk (OPC) page for St Stephen by Launceston where it also says:

The Parish of St Stephen-by-Launceston is now part of the United Parish of Launceston, the other parts being St Mary Magdalene, Launceston and St Thomas-by-Launceston.

and under its SUGGESTED READING section:

the parishes of St Mary Magdalene, Launceston, St Thomas-by-Launceston and St Stephen-by-Launceston are interrelated

The two churches are only 0.4 miles (650 metres) apart so it would seem likely that there have historically been movements and close ties between the parishes and their parishioners.