If you dispel one of these spells, does it remove it from all recipients? Would it require an area dispel or targeted dispel? Do you have to target the caster or will any of the recipients matter or do you need to dispel each separately?
The following spell is for use as an example of a communal spell.
Protection from Law, Communal: This spell functions like protection from law, except you divide the duration in 1-minute intervals among the creatures touched.
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This wording leads me to conclude that the only difference between the Protection from Law spell and the Protection from Law, Communal spell is that the effects duration may be divided among different touched targets.
This means that a counterspell situation would be able to cancel out the communal spell prior to the spell completing, or you would have to dispel each individual target as they are now under the effect of the Protection from Law spell independent from the caster. In this situation it is best to look at how you would dispel a traditional Protection from Law that was cast on a target other than the caster.