Hi all, I've got an important question:

when new GS are spawned at the end of the Event Phase and that spawn happens on the position where already is a group of GS, does this new spawn make a new group or should it be added to the existing group making a bigger one?

I'm asking about that because nowhere in the game manual and in official FAQ I couldn't find any information about that.

The only situation when merging of different groups of GS's is involved is when reorganizing formation after the death of a Space Marine.

Every help will be appreciated

Sorry if my English isn't flawless, but it's not my native language...

It's not explicitly stated, but:

"A swarm of Genestealers is defined as all face up
Genestealer cards on the same side and position of
the formation." (p. 12)

In general, you can only have 1 swarm on each side of each position. With the formation shifting part where a swarm that hasn't attacked not yet merging being the exception. So if you spawn into a position that already has a swarm, that swarm gets bigger.

Thanx, Dam - that obviously clears a lot of my confusion

And also means that in our last game we were extremely out of luck, with two Marines in the last room, and a four GS swarm on the left and eight GS swarm on the right side...