Hi I have been looking at the carb of the porridge and it's 17g and the bars are 16g but you can only have one bar a day because of the carb content. Does this mean you can't have a bar and porridge in the same day?
My understanding is you can have 3 porridge a day of you want to as website says content is similar to that of the shakes and soups. Based on that I woudl say it is fine to have porridge and a bar in the same day.
I often had porridge and a bar - do what feels right to you. Its a very low calorie diet - it works. Don't worry too much about a few grams either way. After a while you will get bored and a bar and porridge will not feel right, then other delights await Soup perhaps? Just drink lots of water whatever you do , then it works.