Is it possible to use nsupdate with EDNS0?

[Fumiya Obatake]

Is it possible to use nsupdate with edns0?

Hello, all.
I have some questions about nsupdate.

I try to update a set of TXT records over 512 bytes in all by using
nsupdate without -v option, and it makes TCP connection automatically.
In RFC2136, `An update transaction may be carried in a UDP datagram,
if the request fits, or in a TCP connection (at the discretion of the
requestor).`, so I guess this behavior is due to the not fitting
request packet (since over 512 bytes).
But RFC6891, EDNS0, should be able to use over 512 bytes DNS message.
I think this is applicable to DNS update, but no one refers to it as
far as I can see.

My question is:
1. Does it violate RFC2136 to use EDNS0 with DNS Update?
2. If not, does BIND have any plan to implement nsupdate with EDNS0?
3. Or, is any other solution to update over 512 bytes message by UDP?

Best regards,