So last night I sat down to organize my Grey Knight Terminators to see how many more I needed to make my Brotherhood Terminators 10 man......cause why not. There are 2 squads that have 8 men, 2 squads have 7 and the last 2 have 6 men. I have 2 unopened boxes of terminators so another 2 more would allow me to max out the 6 squads with Apothecaries and Ancients I could then add ancients to my Paladin squads. 

Below is my Terminator Armor 2nd Brotherhood. (Not Shown is Variant Grandmaster in Nemesis Dreadknight) 

If I max out the squads, I'll have 69 suits of terminator armor for my Brotherhood. Plus with My 3 strike Squads, 2 Interceptor Squads, and 3 Purgation Squads all at 5 men, I would have over 100 Grek Knights in the Brotherhood.