How to link one point to Null and using the rest of the points naturally

Hello all ,

Please i want to know if there is any way to link a point to null for example : I create a square and it has 4 points and I want to link one of his points to Null and With the possibility of controlling the path of other points in normal

Thank you

test file .ae

https://1drv.ms/u/s!AsWsbi63c96Kt1EKjadl-CsKC4LQ

Thank you for understanding what I want

I motion the characters and I need to manipulate the path and move the keyframe animation in frame by frame

This feature is excellent for connecting in but I want to solve the remaining points and manipulate them freely

Please Solution We have waited for this feature a lot

Thanks
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