[quotePost id=122381]Hello,

In a particular Bell FM Part, I can only add 1 destination to an MS lane. When trying to add a secondary MS lane, I even cannot see the "+" button to chose a destination.

Why is it blocking ? Due to the FM side of the part ?[/quotePost]When you can’t add a Destination in the Control Assign area it is because they are all occupied.

There are 16 Control Sets per each Part — a Control Set consists of a “Source” (Controller) and a “Destination” parameter, plus all the parameters that determine how it will be controlled.

They are listed on the Part Edit > “Mod/Control” > “Control Assign” screen.
You will see 4 PAGES, each with 4 numbered Destinations.
_ The Destinations are numbered 1 thru 16.
_To make viewing all assignments easy: find the “Display Filter” set it to “All” (fully clockwise).

If you programmed the FM-X sound yourself, you would be very aware of each of the assignments because you will have had to program them, one-by-one. (Congrats, most folks do not use that much in terms of control assignments).

If you are using the FM-X programming of someone else, then it is imperative to review each of 16 assignments: you do so by selecting the Destination, (hint: use the cursor arrows to navigate the Destinations - this lets you view / tapping it is how you change the assignment).
Highlight and review what the “Source” (Control) is, then try it out. See if it is an assignment that appeals to you in the instance you are working with. If so, keep it.
If not, use the DELETE box in the lower right corner of the Control Set screen to remove it. This will free up that Destination for you to make your own assignments.

If you are using a Library programmed specifically for the FM-X engine, the programmer may have pre-assigned all 16 Destinations (to save you the trouble (? I guess) — if that is the case, your studied review of the 16 Destinations will also bring that to light.

Simply reprogram any of them you are not going to use, or DELETE them and create your own (highly recommended!)

Other Possibilities
Since it is a Motion Sequence there are other possible reasons… any Performance can have a maximum of 8 + 1 Motion Sequence Lanes active at one time (that’s including the dedicated Super Knob Automation).
__ The “8” refer to the MS Lanes that can be applied to the Performance Parts and Common functions.
__ The “+1” refers to the Super Knob Auto (Motion Sequencer).

You can review your current Motion Sequence Lane usage as follows:
From the HOME screen:
Tap “Motion Control” > “Motion Seq” > here you will see how many of your eight Lanes are in use and where they are active - to which Part or whether to the Performance Common/Audio.

If it already shows “8/8” then all 8 Lanes are already in use.

[quotePost id=122383]
There are 16 Control Sets per each Part — a Control Set consists of a “Source” (Controller) and a “Destination” parameter, plus all the parameters that determine how it will be controlled.

They are listed on the Part Edit > “Mod/Control” > “Control Assign” screen.
You will see 4 PAGES, each with 4 numbered Destinations.
_ The Destinations are numbered 1 thru 16.
_To make viewing all assignments easy: find the “Display Filter” set it to “All” (fully clockwise).
[/quotePost]
You made me spare weeks ! Thank you. Actually tens of destination were used for several other sources than MS lanes that I did not check at all. Using the "All" filter made them appear suddenly.
Thanks again.

Actually tens of destination were used for several other sources than MS lanes that I did not check at all.

You'll run into that a lot if you use a preset performance as the 1st step in creating your own performances.

The presets are often used as SHOW PIECES to demonstrate what is possible. As such, they often cram a lot of functionality and even odd ball uses into one package.

They also have a lot of extraneous programming that isn't even used anymore. Extra elements that aren't needed and even extra parts that aren't used and even have keyboard control OFF.

A common suggestion when you want to create a new performance based on a preset is to go through that preset with a fine-toothed comb so you know where all of the programming is. That is easier said than done.

Once you have 'cleansed' a preset to a starting point you like you should save that CLEAN version as a user performance and use it in the future to build your new performances on.

That way you will slowly build up a 'library' of building blocks that you have detailed knowledge about what they do.