No you will not have to open another channel to make another transaction to the same merchant. I previously replied to your topic where you asked the same question and I assume this will be the first and that will be the second topic. I think you are overthinking here and being frustrated to spend a fee that you don't want to spend at all costs, in your previous post you said you only wanted to spend 20 cents and I said if you are using BTC then you can't make a transaction by paying 20 cents even with Lightning because there is the normal fee you have to pay even at the first time.

I think you should not overthink the fee and if you are that serious about it then try to use your fiat currency and then buy some other token like the ones I mentioned in your other post which are BNB or Matic because these will cost you a lesser fee. I am saying it because you can't swap your BTC into another token in Electrum because Electrum only supports BTC. And to make a swap you still have to spend some money on the fee.