The caravan may have noticed the flight of the matron and her followers. It was rather strong visual display after all.<br/><br/>Anyways Mind Blank conceals you against from scrying and other location finding divinations. But mind blank does not stop legend lore, divination (so long it does not ask your present location) so I would rule true seeing does go through your disguise as yochlol. But the actual trick is that you have several 'true forms' same time; so you look to true seeing a shifting mix of comely female drow, a spider, mist and then slime wih one red eye and tentacles. All those forms are tightly part of you.<br/><br/>So, true seeing would reveal to anyone who is student of planar knowlegde that you are yochlol.