You are best off separating Vallis from the pot, some plants seem to do fine in them I for one kept an anbuias for a long time in a ceramic pot before the wood had soaked enough to hold itself down.
It might come with rock wool or rolled cellulose sponge in which you merely just unroll. What you can do with the rock wool is separate the plants gently. You can easily identify what belongs to what in terms of stems. You can use the rock wool as an anchor by leaving a little on the roots to plant in the gravel since I have always found it awkward to plant thin rooted plants in gravel or sand without the rock wool. It also helps avoid the impending struggle between man and plant which usually results in a few broken leaves. Leaving a bit of rock wool on won't cause your plants any harm when using it as an anchor, most plants absorb most of their nutrients through their leaves in from the water column hence why we put nutrients into the water. Just make sure you re plant them as individual plants.
Like someone previously said the Vallis reproduces by runners, once established they tend to spread like wildfire under the right conditions. I would advise not letting it get out of control and you can keep it in the area you want by simply trimming the runner back.
I personally love the effect you can get from Vallis, just a word of warning though I have struggled many times as my water is pretty soft and dosing things like Easycarbo/Excel can cause complications.
Edit: Once vallis leaves begin to die it's best to remove them as soon as possible from the base of the plant.
