How to merge/change sub-basin size in ArcSWAT?

[Shashwat Dhungana]

Dear fellow SWAT users,

I am trying to run SWAT for a catchment of interest in South East Asia. The watershed delineation process generated around 21 sub-basins for the basin. However, upon closer inspection, I feel that it would make sense to merge some of the sub-basins because they are comparatively very small and have similar landuse and soil characteristics (see basins numbered 1,2 and 3) in the following figure. 

How can I merge these basins? Is there any straight forward way to do this? I am aware changing the threshold area would alter the size and number of sub-basins but I am hopeful there might be another way. 

Please help! 

Sincere Regards,

SD