If I get too simplistic, I apologise, but it may help to go back to basics.
Presumably from the baptisms, you have parents' christian names, so I suggest you get some paper (it has its uses!) and put down 1 couple per sheet, starting with those who married in the parish.
Then from the baptisms add the children to those couples.
If you have two couples with the same name then this is where the fun starts. Children generally appear at intervals of approximately 2 years. You can expect to find both the parents' names repeated for their children at some point. A woman from outside the parish might bring in different names, which may help. However, if the families are related then they start naming their children after the new aunts and uncles!
If you can to the census records, that may help with groupings. Also look for burials - after 1812 the age has to be given in the register, but it won't necessarily give relationships. However an infant burial might explain a birth less than two years after the previous one in a family.
Does this help - or are all the couples called John and Mary?

Nell