I'm still pretty new to Fantasy Grounds effects, but as described Guidance would then apply to all rolls.
With that said, your answer lead me to a version of what you described that seems to be working great for Requested Rolls!!!
Changing the effect to "Guidance: 1d4; (C)" handles both the concentration of the original caster *and* triggers the requested roll for the consumer.
With that said, it's still useful to have the "self" effect on the original caster as a reminder they are maintaining concentration on something. So I can see using both, but this is going to help a lot.
Thank you.