You can set the TakeNextMajorOnMerge option on the merge method, so that SmartPlant Foundation always uses the next major revision in the parent configuration when merging a document.
In the illustration below, the document was revised from Plant A into the different projects as separate minor revisions. If the TakeNextMajorOnMerge option is not set on the merge method, SmartPlant Foundation tries to keep the current revision.
This can be confusing if used with one revision scheme.