Setting up security on Option set items

Hi Everyone,

I am facing a challenge with setting up security on an option set. 

I appreciate any suggestion.

I have an entity called Bank Deposit with a field called Deposit type.

Deposit type = Global Option set with 3 options

1. Cash

2. Cheque

3. EFT

Now the challenge is that Some Bank Deposits have only 2 methods: Cash and Cheque

1. Cash

2. Cheque

3. (EFT Hidden)

I created a form for BD ( with EFT)

and one for BD (without EFT)

but how can I hide option for EFT on the 2nd form?

I understand i can create a 2nd option set with 2 items but i have tons of workflows using this option set with 3 values that it wont make sense to change everything.

Is there a way to do this without code? If not, can you think of a better method to do this?

Many thanks

Elsa