Best way to handling forwarding of midi controller information between vst3 and vst2


I’m developing a plugin at the moment and am sending edited midi (including controller data) to an external plugin (any random vst) sort of like a simple harmonizer that adds some controller data too (this part is all fine, apart from sending the controller data to VST3). This needs to be done within a DAW that doesn’t support midi inserts or midi sends, so having the plugin itself host the “target” VST seems like the best option? However I need to be able to host both VST2 and VST3 - are there restrictions on doing this, and what’s the best way to host a plugin within a plugin?

Additionally, from what I’ve seen on this forum, VST3 seems to handle midi controller data as parameters or something, do I need to send out both midi controller information and find the parameter just incase it’s a VST3? Or is there some better solution I’m not aware of for this?

Apologies if anything is not clear!