I would talk to them and let them know that I need a certain amount of communication from them in order to keep my team on track. I could reach out to them and see if there is a better way for them to stay updated and keep others updated. I could make sure that there are thorough minutes taken during meetings to keep them updated. I could ask them if there a good time to contact them so I could fit better into their schedule instead of forcing them into mine. If after trying to work with them in multiple ways still doesn’t result in effective communication and it starts to affect my team in a negative way, meaning missing deadlines or creating lulls in the development process I would have to ask for them to be removed from my team and replaced with someone else.