trouble with substitution drawing when adding in-betweens

i have a keyframe 1 with the whole character and a keyframe 2 with the character’s head as a substitution drawing. as i now make place between the keyframes to add an in-between, the head of the added frame disappears, although the bounding box remains. the keyframe has nominally the head from the kf 1.
can anybody explain what went wrong?
thx, rob

unfortunately i can’t upload any picture, the (strange) error message says:
‘The file is 33.61 KB which would exceed your disk quota of 1 MB.’

You should have a separate body part element for each body part. You only use drawing substitution to replace the same body part with a different version of the same body part (for example and open hand can be substituted for a fist).

You may wish to review the character rigging tutorials before proceeding because you could potentially waste a lot of time if you choose the wrong method of rigging for your particular character/project. It’s always better to take a little more time in the design phase than having to fix things later once you have already commited yourself to a specific workflow.

and the exchange parts are the head position keyframes (profile, 3q a.s.o.), as shabana explained them in the educational videos.
obviously there’s only one way to insert those elements, and this is the position when the dragged part gets an orange rectangle, enabling the inserting into the rig structure. thus the head changes its position.

the trouble starts, when i make place for additional drawings, moving the sequence part: in the new frame, which gets created between the one head position and the other one, the head drawing disappears, although the bounding box remains.

i start to suspect that the software is not sure, which head position should be in-between, and for any case displays none.

anyway, it seems to me that the exchange of the body part’s positions is only possible, when all frames are in place, but i may be wrong…

It depends on the keyframes. If you are inserting a drawing inside a sequence for a particular body rotation, it should apply the position correctly. Check if the position of the new drawing matches the rest of the drawing in the sequence (using a grid).

Inserting a drawing between sequences requires more work so I would insert the drawing before the last drawing of the sequence. You could even put a placeholder image as the last image of the sequence if inserting images puts your image sequence in disarray (ideally planned at the beginning of the character creation, to be truly useful as a technique).

i am aware it’s a bit unnatural to break the sequence or to substitute its drawings, but i really like the way stacey eberschlag conducts his animations (as displayed in the educational videos provided by toon boom).
i make the keyframes, then adjust the positions, then add more keyframes and adjust again.
next, having all important keyframes in place, i adjust the timing, moving the keyframes around and inserting the in-betweens, either motion or static.

in this way any body part’s position change (inserting of the templates of other views - 3q or profile, stored in the template library) may result in the situation described in the initial post. again, it seems that the best workaround is to change the drawings when the whole sequence is already keyframed and with correct timing, so no more frames’ insertion is necessary.
thanks again for your time.