I want to know if you can run 2 exhaust fans from 2 diffrent boxes out one vent. The exhaust vent hole is 8 inch with a 8 inch duct to a box with a 8 inch inline fan inside it. The other box has a 6 inch inline fan with 6 inch duct. Is running the 6 inch into the 8 inch going to have air flow problems? Both fans will be on at the same time. Thanks.