I do not know if it’s useful, here’s an example of positioning and blending.
# example blending
# Gmicky 2w*1h
rm[0]
fx_gmicky 2
resize[-1] 200%
# variables
Color_Tolerance=10
Maximum_Number_of_Output_Layers=2
Minimal_Area_PourCent=8
Autocrop_Output_Layers=0
W_Origine={w}
H_Origine={h}
# 2 layers
quantize[-1] $Maximum_Number_of_Output_Layers
fx_split_colors[-1] $Color_Tolerance,$Maximum_Number_of_Output_Layers,$Minimal_Area_PourCent,$Autocrop_Output_Layers
to_rgba[-1,-2]
# Gmicky rgb
+fx_gmicky 0
to_rgb[-1]
# where you want to see Gmicky
expand_x[-1] {abs({$W_Origine-{w}})/2},0
expand_y[-1] {abs({$H_Origine-{h}})/2},0
# blend alpha
blend[-1,-2] alpha
rv[-1,-2]
