Quote from: digaran on Today at 09:11:02 AM

I know it has no accounts, but OP is asking: if he sends 1 transaction combining all 3 inputs from 3 different address types, which address the receiver sees?

The receiver sees the transaction, which will clearly contain all three addresses. How his particular wallet software displays that transaction may vary, but all three addresses will be part of the transaction.

Quote from: digaran on Today at 09:11:02 AM

Or how do you sign a transaction that has 3 inputs from 3 different address types?

Either import all three address types (and their relevant private keys) in to the same wallet, or move a partially signed transaction between three different wallets, each containing one address.

Quote from: digaran on Today at 09:11:02 AM

Would you need to first send from 2 address types to the third address and then send out whatever you want to your friend?

You could if you wanted, but there is no need to do this.