There are two considerations to take in when moving workouts around or creating your own plan: recovery and frequency. You want to be able to recover between stressful workouts, and you want to space out the 3 sports relatively evenly (it’s better to swim 3 days every other day than 3 day on 4 days off, for example).
The recovery period from swimming is so brief that you can move swims around with ease and not worry about the recovery. In fact, we often have an intense swim and intense bike or run in that same day.
So, all you have to do is worry about frequency. In your case, if you just have to take the week-end off from swimming, as long as you swim each Monday you’ll never go more than 2 days without a swim, and that’s just fine.