You would need to create opportunities and experiences in each language where you can use the two words considered “faux amix” to distinguish their separate meaning and use for the child. The child learns vocabulary meanings in context and with use. So, the parent or teacher should create experiences for the child that provides them with explicit exposure to how the meaning and use of each word is different, even though the words appear to be cognates.

I haven’t explored the use of sign language as modes of communication but investigating that avenue through a multimodal lens would be highly interesting.

Gestures of all sorts are definitely signing, but I would say they’re a different “signing” than what ASL would represent. Gestures in the way that we study them could definitely not be categorized as their own language in the sense that they are used to accompany other forms/modes of communication and may not mean what they intend to mean if not interpreted with those other forms or modes. This also stands counter to multimodality theories that treat all modes as semiotic choices in communication that exist on the same continuum, and none which are meant to be separate out or treated as individual/disconnected from the overall communicative repertoire.