[Solved] How to eliminate gap when joining not-looped splines

I’m trying to combine two splines with regions by linking two vertexes of each spline. the splines remain unlooped at the junction. it works, but there is a small gap separating the regions of the same color. how do I eliminate this gap? Feathering doesnt seem to accomplish this.
To make my design more clear, Im trying to create a sweater consisting of 3 regions and outlines (two sleeves and the center part) without having black line seperating the sleeves from the center.

In “Parameters” panel unset “Antialiasing” option for connecting region layers.

great. thank you so much.