Estimation via SURE model(Seemingly Unrelated Equation Models)

Today, 00:43
dependent variable
delta_cash short term debt long term debt
intercept
working capital
R&D
Net income
My questions are based on the above table. Suppose, I have equations like
delta_cash=intercept+working capital+R&D+net income+error, so on and so forth. Thus I have 3 equations.
I need to estimate this by SURE(seemingly unrelated regression equations model). I would like to impose certain restrictions like
-α_1+α_2 +α_3==0(That is -ve of the intercept in first equation+ intercept in the second equation+intercept in the third equation should be equal to zero. Similarly -β_11+β_21-β_31=1


The first subscript of the beta coefficients indicates the column (i.e., the dependent variable) while the second subscript denotes the row (independent variable).
I am not much experienced with Stata hence I used the menu way (Statistics<linearmodels......) for SURE but I am unable to put my constraints. Kindly help me to sort this