Is ther any rol of montilukast in copd other than asthma/?

Probably not: I have never used this for copd, and it is not officially indicated for this condition. I have used it quite successfully for asthma and allergies, though.

If allergies also: If allergic criteria can inpact lung function and this med can help.

NO: Singulair ( montelukast ) in indicated for asthma prophylaxis and chronic treatment, for seasonal and perennial allergic rhinitis, for prevention of exercise-induced bronchoconstriction. There is no indication to use in COPD - different mechanism of the disease. If you have allergic rhinitis which worsen your COPD symptoms - probably it could be beneficial.