I attach the marabou two different ways, depending on how I tie the chenille.
If I'm wrapping the chenille over Fireline, I'll tie it on a small light wire trailer hook first and wrap the chenille forward. I then cut the trailing hook off.
If I'm braiding a chenille or estaz tail, I make the tail first then tie on the marabou afterwards. I'll then attach the entire tail to the hook.
I hope this helps.