How to add a field to a stack of 50 cards

[Russell]

Hello people

Thanks all for your contribution to my query.

Questions: 
    Does RR use more resources by putting a Field on 50 cards then if you create that field to act as background on the 1st card

    What about creating a invisible group on card 1 when 1st creating the stack and make it act as background.  Then after 50 or a 1000 cards, if you decide you need another field, goto card 1 edit the group and create yout field inside the group. Would that work?

Thanks

Russell