The compilations are almost always allowed, but technically it still requires a formal approval.
I think the industry thing to do when receiving permission is as they did with Mark Linkous on Fear Yourself: "Mark Linkous appears courtesy of Captiol Records"
If it isn't otherwise intuitive that such arrangements are "necessary", then to explain it we'll need to list all the reasons that music artists and record companys HAVE contracts.
But here I'll ramble for a bit:
Most music artists aspire and HOPE for getting a contract with a record company. This suggests without exploring why, that they think this is to their benefit.
For anyone who aspires to MAKE A LIVING from their music you've got to partner with people who can do these things AND bind yourself contractually. I don't think there are many exceptions to this - although it does look like Townes Van Zandt's wife is doing a lot of direct-to-market sales.
http://www.townesvanzandt.com/ - or until you're "big enough" to make and promote your own label.
Many people recognize the problem and work in a very good-willed fashion with Daniel - and normally they have agreed with Daniel and his father not to make such decisions spontaneously or alone with Daniel. There is the contractual obligation AND there must be some "plan" to it all.
Those who don't do this impede (intentionally or not) efforts to sustain Daniel from his work.
Daniel LOVES to record - he loves to do this with friends. and he's a very generous guy. Like you suggested with your friend that you had to warn them or they "would have had a heart attack" when Daniel said "We just recorded my next album" - Daniel's heart and enthusiasm far exceeds his prudence and concern for other commitments. As you said, we just have to recognize and take it into account when working with him.
There are at least two full albums of material ready to publish, but they will publish one this year (besides the Tribute)
There is the side of the music making that "wants to give it away and share", and rejectedunknown.com has taken that perspective on quite liberally. There is as much joy in "just sharing" all Daniel's work as in hearing it.
Daniel did some recording with Jad Fair earlier this year, but Jad understands and agrees that it cannot be published any time in the foreseeable future. The reason is "for Daniel's benefit".
Okay - I've already way over-responded... I won't tell you how much I went back and trimmed out!!!!
In summary: An artist typically cannot make financial gain on his own, and unrestrained publication of the artist's proliferate material harms efforts to make money for the artist.
Daniel occasionally ignores this verbally, but he does know it - and he has legally bound himself with contracts.
I hope that a lot of all the stuff Daniel does everywhere will eventually be published in some measure. But sadly for Daniel's sake we must temper our enthusiasm and just "hang on to" the material for now.
Come to think of it, that's what the MEMBERS ONLY area is trying to do - to share "some" of the good unpublished stuff with a limited audience ("hard-core fans") and done in a way that doesn't hurt the finanical efforts.
You know, if you just "have" to share some of the material, you might work with Rejected Unknown and share it in that "approved" and restrained context.
Otherwise "YES", Daniel is bound contractually it cannot be ignored. Anyone in possession of such recordings might "share" it, but it cannot be "publshed" in any quantities or sold.
YES - anyone should check with his father or brother before publishing anything and they have to make decisions based on existing (multiple) contracts and at least some "vague" strategy for Daniel's well-being.
Best advice: - anyone who is holding any such material might have the greatest chance of some of it being included in compilations or some other medium if Daniel and his father and brother had copies of it. It would be used along with everything else for compilations, etc.
As more magazines and colleges, etc. publish compilations, that WILL be from Daniel's "unpublished" material - both to stay inside the contractual lines and to keep it all interesting for new and old fans.