Here is some progress that I can share although it's still not perfect.

• I created an extension of MessageContentCell with a new method to set the Forwarded label. In the method, I insert the label and change the frame of the messageContainerView (increased height)

• then in my viewcontroller showing the messages, I increase the height of forwarded messages cell using collectionView sizeForItemAt

this works nicely except that the increased messageContainerView will only show if I scroll up and down to force the cell to redisplay itself. I have tried to various approach after changing the frame (layoutIfNeeded, setNeedsDisplay, setNeedsLayout, layoutSuviews, etc...) but none help.