I was happy with my understanding of battlelines but a friend at the club has read the rules and has a different inturpretation to me. Can you please confirm which view is correct.
My understanding is that Battlelines are essentially a manouvre thing and quality rerolls can be utilised for CMT etc based on lowest quality unit. The rules for Battlelines do not figure in combat at all. Both impact and melee (combat, cohesion tests etc) are resolved by individual battle groups and so each BG uses its own quality reroll accordingly.
My friend has suggested that the rules for Battlelines are also used in combat and so an impact or melee with mulitiple battle groups on one (or both) side(s) in a line means that the lowest quality reroll will be adopted for all BG's involved in the combat for that side.
We have both found bits in the rules which support our own view.

Bit of a basic question, but clarification would be gratefully received!

Thanks
Nick