I am not sure if this will help but if you are looking for a grave rather than a burial that may be the stumbling block.
Often people of modest means could not afford a grave,babies and small children were often buried with other people not related to them.A communal grave.
My mother`s two baby brothers were buried in such graves with twenty and twenty two people respectively. Both are properly recorded but are on top of a lot of other people.Then more on top of them.
You may have explored this avenue and if so I apologise.Viktoria.