Strange party increase - I wanted to send ONE attack unit in mining party!
The issue was in the way.
I researched Lost Art of Oath of Faith and I selected 1 Imperial Seeker as attack unit in mining party (I received it as reward just before).
I sent the party before I finished 3rd level of the Lost Art.
I got a message about reward for level completion.
BUT then I got a message that I clashed with other mining party (it happens). However most strange, my attack party had 3 (THREE) but not 1 (ONE) Imperial Seeker!
How this was possible at all?