To Group Items In Bed Files

For example, we now have a bed file:

chr1 23455 45678
chr1 23446 45663
chr1 23449 45669
chr1 30000 31000

Is there anyway to group the first three lines, while leaving the last line alone? I know Bedtools have mergeBed function, merging those overlapping span, which, however will include the last line.

This may sound a pure computational question; but I'm just curious if we have available tools already to tackle such questions

thx