In EDB can you have a building branch at some point so that one level has two potential upgrades?

So something along the lines of:

Code:
building b1
{
    levels b1, b2, b2a, b3, b3a
    {
        b1 requires factions { barbarian, carthaginian, eastern, parthia, egyptian, greek, roman, } 
        {
            capability
            {
                something
            }
            construction  2 
            cost  600 
            settlement_min town
            upgrades
            {
                b2
                b2a
            }
        }
        b2 requires factions { barbarian, carthaginian, eastern, parthia, egyptian, greek, roman, } 
        {
            capability
            {
                something
            }
            construction  2 
            cost  600 
            settlement_min town
            upgrades
            {
                b3
            }
        }
        b2a requires factions { barbarian, carthaginian, eastern, parthia, egyptian, greek, roman, } 
         {
             capability
             {
                 something
             }
             construction  2 
             cost  600 
             settlement_min town
             upgrades
             {
                 b3a
            }
         }
 
etc....