Using CarryOn and Better Survival 1.3, adds a 3rd arm to the player while carrying a block:

I've talked with the dev of BetterSurvival and they are using the same method for rendering arms, which overlaps with our way. We will see if there's alternatives, to prevent further incompability, but the BetterSurvival dev would also have to update his code.

Mynko is not having these rendering issues. I contacted Mynko's Author.

@capnkirok Better Survival handles it like we do, dunno about Mynko

My recommendation is that Better Survival borrows our technique for showing/hiding the left arm, and only shows it when the player is not carrying. They could check for a child to the Body with our exact Rotation Angles and choose not to render their swinging arm if this child exists.

Let's point them to our git when it's up.