Alexander Galkin wrote:

I have 2" vent in my house that drains almost to main drain pipe very low in
basement and goes to the roof through 2 floors. Currently several fixtures
on first floor bathroom and kitchen sink (also from first floor) are not
vented at all. There are two vents going through the roof: main stack vent
and this 2" vent. I installed sewage ejector in my basement and want to vent
it through 2" vent, I also want to vent through this vent all other first
floor fixtures that are not vented now. Can I do this? I know that
individual vents must connect to main stack vent at least 6" above highest
fixture flood level. Does this requirement apply to my 2" vent? It is only
vent, nothing drains to it. I also don't know if any fixture from second
floor bathroom is vented through it.

I don't see any problem with what you propose.
Doubt that you will be exceeding the maximum number of fixture units
allowed on a 2" vent.

If the kitchen drain isn't causing any problems now (gurgling,
self-siphoning), I wouldn't spend a lot of effort venting it;
it was commonly allowable practice in the past to use an oversize
drain which would then act as its own "vent" for kitchen drains.

Jim