At the moment I just load the chain into an empty channel, but it would be easier if I could load it on top of the existing effects…
Is this possible?
Maybe load it onto an effects channel, and use the SEND effect on your current channel with effects to point towards the effect channel.
That should do the trick.
p.s. better late, then never reply 
Don’t think its currently possible but you could add the new dsp-chain to an empty channel next to your original channel and then (using the mixer-view) move the dsp-effects to your original channel.
Currently this is the only way indeed.
Chains are written as full chains and replace any existing chains. This goes for copy and pasting chains as well.
Cheers, I’ll just keep doing it the way I am now 