Hello Blake - see the link. This is pretty much how I braid raffia - multiple strands in a multiple braid (plait) Procedure is to assemble the 3 or however many bunches to be plaited. Secure at one end in a tight binding, then tie a loop of string around the binding with enough left to attach to a stationary spot - I use a coat hook, but a toe works, as does the back of a chair - just be sure the string is long enough! Once in place the tension is sufficient to braid against - separate your bundles of sweet grass again and off you go. If the sweetgrass is dry, it may be easier to plait if it is damp - spray with water lightly and roll in a towel for 20 minutes or so before you start. If you find how the first nations peoples plait it, please post
https://www.ictinc.ca/blog/indigenous-sacred-plants-sweetgrass