Hi, you asked in another thread if I could help. In theory, I have room for your 5 but getting them to Colorado would be the tricky part. Since you don't really want to rehome but want to take care of them, I would go ahead and try to keep them if I were you. You took them in 4 years ago so you have a decent amount of experience already.
First off, it's never too late to try to bond with them -- there are a number of tricks offered in this forum as well as at glidercentral.net but the first to start with would be cutting up little fleece blankets (maybe 2-3 inches across) and wear them against your skin all day then place inside their sleeping pouch. Start doing this immediately and replace the fleece with freshly odored (meaning YOUR body odor) ones every couple of days.
Next, make sure you briefly handle the joeys daily so they WILL bond with you.
Since you're afraid of inbreeding, I take it at least one of the "babies" is female. You're going to have to neuter Dad right now; how old are the "babies"? The males will need neutering as soon as they're old enough but I'm wondering why this hasn't been a problem over the past 4 years? Since your vet hasn't done this before, I would look at the vet database and seek out recommendations for an experienced vet to do the neuters.
If all else fails and you really need to rehome them, we can talk but we're going to have to work out shipment or a railroad to get them to Colorado. I don't have time to do a long road trip to/from Indiana.