Hello,
my baseline model is the following:
Code:
 xtivreg2 y l.y $controls trend (x1= z1 z2),fe gmm robust bw(1) //
Where x1 is my variable of interest and z1 and z2 are valid instruments.

I would like to expand my model to include an interaction between x1 and x2. x2 is another endogenous variable for which I have valid instruments (z3 z4). Does anyone know how can I interact with two instrumented variables using xtivreg2?

How can I specify the interaction with multiple instruments into xtivreg2?
The specification below is wrong but perhaps it is a starting point to address the question

Code:
xtivreg2 y l.y $controls trend (x1 x2 x1#x2= z1 z2 z3 z4 z1#z2#z3#z4),fe gmm robust bw(1) //
thanks a lot in advance for your help Best Regards