Assuming that you were asked/tasked with the tole of being your department’s lead for the integration, I would assume someone with authority had to select you. I would suggest documenting what you have done and been trying to do in a summary format and presenting it to that person. That shouldn’t be done in a complaining way but in a factual way, reporting the key items on the department’s integration action items, what the statuses are and what needs to be done. If there are management levels between you and the person that picked you, copy the others, so they don’t get surprised or think you are going “around them”. Even this carries some risks but might get people who are using passive-aggressive methods to undermine the transition moving.