Can you fill in the missing numbers of these number sequences?

> 
> \_, 3, \_, 9, \_, 14, \_, \_, 21, 27, \_, 35, \_
> 
> 
> \_, 7, \_, 15, \_, 22, \_, 30
> 
> 
> \_, \_, 5, 7, \_, \_, 12
> 
> 
> 

The three sequences may or may not be linked together in some way. If you can come up with the missing numbers, please provide an explanation.

I have tried to solve this for about a week now and I've gotten nowhere, hopefully someone here comes up with something.