Are the pieces glued?
I usually place greenstuff between the pieces BEFORE gluing them.
You can either put glue on both sides and squish some wet greenstuff in, or secure the two pieces together with GS, separate them when the putty has dried in the 'fitting shape' and then glue the resin bits with the GS adaptor.
If you glued the pieces without the GS, and they hold well together, you can use GS to fill the gaps.
In that case I use a craft knife to apply tiny 'worms' of GS where needed. To avoid mess you should keep your blade and fingers wet. Keep the gap you want to fill dry and clean, apply water with a brush to the nearby areas where you do not want the GS to end up, then apply GS.
PS did the left pendant from the palanquin break?
PPS Why do resin Slann models have different curvature on the horns of the two sides of the palanquin? The left side horns are aways more bent. Is this
Btw after i touched the right pendant it give in aswell xD