When people were truly poor, a rich relative, who owned a grave, might allow poor relatives to be buried in their plot. My own Grandmother is in her brother-in-law's plot as he only had a wife but no children so there was space that would not be used. As previously, you needed "spare" money to afford to have a grave and even more money to afford a headstone (& even more money for extra names to be added). This could result in someone being buried in another graveyard. In the canal families, a child died in Salford but was buried in Burscough (but that was in the 1900's). I know this doesn't really help your search but, if there is no note as to burial place in the written records, you may be unable to solve the riddle.