The whole argument that "Zombies limited to 10" BS. Everyone with any sense knows GW will FAQ to say yes Zombies can go up to 35 per unit. Now the issues; "and cannot purchase options" everyone assumes all options when the only option you can actually purchase are the Marks for the whole unit. All other options are either "add to", "exchange", "or replace". The weapons are dealt with in that zombies only get a single CCW and guns are used for clubbing. Sorry to split hairs but people are really whining an over-reading to much into the rules. So short answer, yes you can add to the unit thus getting35 zombies as it's not a purchase. You just can't purchase "Marks of XXX"
Seriously it's not rocket science.
Meant stop being stupid lol