Yep...the name of the module you're looking for here is a "diode OR"...it actually fits into the "Logic" category, as it passes a gate when any one of the inputs receives one, but it's not a "true" Boolean gate. There's also another similar module for combining CV/mods...adders, which have the fun capability of doing what the name means. For example, let's say you've got your pitch CV, but you want this to glide up and down in pitch instead of staying static. One way of doing this, natch, is to mult out a modulation source and send individual signals to each VCO's mod inputs. Which can sort of work...but it's messy and you have to adjust ALL of those mod input levels just right.
But the OTHER, more elegant solution would be to send the mod source to an adder along with your pitch CV. Combine, connect the VCO CVs as per normal. This cuts down on patchcables and hassles in general, and ALL pitch CVs are moving at exactly the same rate without futzing with the individual mod input levels.