As it is clear that your own troops can block you from making contact, this is no more an issue than any other situation where you are blocked by your own troops. The situation would be the same if it were two single based knights instead of a DBE.
Actually there is a slight issue: the presence of the enemy prevents you from moving C to form a group with B. If B and C had already been a group, you could have moved them together into the contact position you want. This might be a bit fiddly to legislate a fix for.