Ayahuasca design not only the association of two plants but rather it's primordial constituant : banisteriopsis caapi.
So ayahuasca has to hold AT LEAST this very plant.
Anahuasca or otehr names have been designed to point out the emergence of other hamalas extract in hteir crude form associated with tryptamine, pharmahuasca in their less crude form, isolated or partially isolated alcaloids.
the most famous ayahuasca beverage contains, caapi and chacruna thought it is far to be the only one, yagé, can be used with or without many admixtures some of them are certainly unknown as of yet.
Chaliponga, chiricaspi (brunfelsia), toé (brugmansia), piri-piri (cyperus articulatus), guayasa to name a few are associated with caapi as an ayahuasca mixture.
Rue isn't a traditional way, it's more based on analogy than anything else.
Now speaking chemistry, everything is addding or substracting to the experience so the alcaloids present, a swell as other compounds, tannins, oxydes, freshness plays a role in different effets.
All I could throw in for now, safe brewing seraph, and tek care !
Smell like tea n,n spirit !
Toke the toke, and walk the walk !