For anyone that lands in here, I've managed to solve this, for full pen check:
Multi Lottie Loading:
I now load all lotties at the top of the script as usual, but I then add them to an array and check the whole array to see if it loaded, then trigger a function that contains my usual gsap / scrolltrigger stuff.
Multiple Timelines
My issue wasn't creating them but getting it to do what I wanted. You can just do timelines then use ".add(tlName)" to add to a master timeline. What I wanted however was to isolate the subtimelines so changing animation duration wouldn't affect the others, this was achieved by adding ".totalDuration(15)" at the last step of each subtimeline.
