You know, I knew I played it that grand cruisers squadroned separately from cruisers and battleships, and have for so long I forgot where I read that, but when I went back through the BFG core rules it simply says under "
Squadrons" that "A squadron can contain up to six ships which must be all of the same type" (BBB pg. 37). I skimmed the 2010 FAQ and was about to post to the thread about "squadron restrictions, waitwhat?" when I found what I was looking for under the "
Ships of the Gothic Sector" section of the core rulebook, subheading "
Forming Up The Fleet" (pg 105):
Escort ships must be formed into squadrons of between two and six ships each (note, FAQ 2010 allows you to field a 1-escort squadron if all you have in the fleet is a single escort). The escorts in a squadron do not have to all be of the same class.
Cruisers, heavy cruisers and battlecruisers may be formed into squadrons of two to four ships. Battlecruisers, heavy cruisers and cruisers may be mixed together in the same squadron.
Grand cruisers and battleships may be formed into squadrons of two to three ships, but you may not mix battleships and grand cruisers in a squadron.
This I'm pretty sure is what Sigoroth's referencing, but like AndrewChristlieb said, everyone has house rules, and it's probably worth noting that these fleet list restrictions are on the same page as the "
Breaking The Rules" box