If you see someone planting explosives and you want to destroy them after he left, you can't !
If you plant an explosive charge next to the explosives someone else planted and you touch it off,
only your own explosive will explode, which is extremely unrealistic and contra productive.
This also applies, if you have only 1 explosive charge and want to blow up a big building :
You try to combine your explosives with 2 or 3 other people each planting one .
If the other 2 die and your objective is to destroy the building the mission will not be complete able
because only your single charge will blow up , even if the charges are all on one pile !