AFAIK, only one chain per event, track, preview or master bus. A few work- a-rounds though include putting a secondary chain on a nested event that already has a native chain or automate plugs in the track or master chains. Pre-rendering to a new track is another option and then add another chain to that track.
I do not recall max number of plug-in can be in a chain, but it is many.
Hello, VEGAS Pro's FX package appling mode is a illogical "replace" way. Applying FX package will delete all orignal plugin-chains.
So does VEGAS Pro's "copy-pastet-attribute". It will also delete all orignal plugin-chains.
Now there are two troublesome ways for your need:
1. Use Vegasaur's "created nested project from selected track" to turn your track to a .veg file. Than add your second FX chain to this .veg file.
2. Add your second FX chain to a empty event. Use Vegasaur's "Effects - Apply/Remove FX" to copy the empty event's FX chain to your video track. Vegasaur's "Effects - Apply/Remove FX" will not delete all orignal plugin-chains.
1 IF you want create nested project - you don't need Vegasaur. I'm using Vegas since Vegas 6 - and you ALWAYS could and can import another vegas project as nested project on the timeline. Just drug & drop it from any Windows' window.
2 IF you HAVE Vegasaur - then read effects with apply/remove effect form "EVENT A", than add to to event B, than read from Event C, and add to EVENT B... and so on... I do it all the time))