The key to having a mod destination (in this case, lfo1 amplitude) completely controlled by a mod source (in this case, m1 wheel, lfo2, or an envelope) is to set the offset at -100%.

To sweep the level (lfo1 mod depth) with m1 instead of the control knob, try this:

In lfo1 edit, set m1>lfo to 0%.

Now in the mod matrix; mod 1 routing: lfo1(sine) >voice pitch, level +30%.

Mod 2 routing: m1 wheel>lfo1 amplitude, level +100%, offset -100%.

Now m1 will control lfo1 modulation level (depth).

To have m1 control lfo1 rate at same time, add the mod routing: m1>lfo1 rate, level +20%. You'll want to play around with lfo1 wave shape and rate, and the level settings in mod matrix.

To have lfo2(saw) modulate lfo1 amplitude, try this: change mod routing 2 source from m1 wheel to lfo2saw, and change the level to +46.4%. (set lfo2 rate at .338hz).

Now make another mod routing: m2>lfo2 rate, level +60%. Hold a note and play with the mod wheels... :)

The possibilities are endless...try using an envelope instead of lfo2 saw to mod lfo1 amplitude...