Kitchen wiring issue
Ok.  The fundamental rule is that currents must be equal in every cable or conduit. 

Yes, current travels in a loop.  But in actual practice, we squeeze that into a "tree" topology.   Imagine you draw a tree on a piece of paper, and send an army of 2-dimensional ants (current) to explore the tree.  They are not allowed to hop across branches, but they can wander from branch to branch without going back to the bottom of the trunk.  At any point on the tree, if you count the total ant passages, exactly the same number of ants (current) go up any branch as come back down. 

This equal flow assures the current does not induce magnetic fields and eddy-current heating into nails, sinks, piping and other metal parts of your house.

Now it's OK to have 3 wires, 10A going out on one, 2A going out on the other, and 12A returning on the third.  That's still equal.  That's how a sometimes-on switch wire can travel with an always-hot.  

Multi-wire branch circuits

That is also how a multi-wire branch circuit works, which is what you have on 14L and 16L.  It's not an accident they are 2 numbers apart; they must be on opposite poles or they will overload the neutral.  

And it's perfectly fine for part of a multi-wire branch circuit to have one side branch off in another direction, as in 16L.  However its neutral must run with the partner hot.  So whatever is going on in 16L, you must make sure that wherever the hot runs, the neutral is right next to it.  

If you're working in conduit, as I suspect you are, your local actual electrical supply house sells THHN wire in 11 colors and tape in 10.  Use different colors.  Gray and white are both legal for neutrals, so when you have two circuits in close proximity, ask them to sell you some gray neutral wire. 

You see where there are points where the MWBC splits off to just one hot with just one neutral.  That is a prerequisite for working with GFCI+receptacle devices.  That is fine, again, keep the hot with the neutral at all times.   Now, a few new Code requirements with MWBC: 

Anywhere both sides rely on the same neutral, the neutral must be pigtailed. You must be able to remove the device without interrupting the neutral wire for either side.

Both sides of the MWBC must have a common maintenance shutoff, which in practice means thet must be on a 2-pole breaker.   When dealing with duplex, you get a "quadplex" that is a 2-pole in the middle and two singles on the outside, like this one.