Then you're turning your 2 of 3 into a 3 of 3. Imaging one of the seeds is in a safe deposit box in another country.
May be I don't understand you but I agree with Charles-Tim here. The seeds are what the OP needs to take care.
, you can recover your funds when you have all 3 keys. The point of using 2 of 3 multisig is that you can recover your funds
without the third private key. I didn't want to type a lot on mobile last night, luckily hosseinimr93 explained it nicely already:
Assuming you have seed phrases A, B and C, for generating your 2 of 3 multi-signature wallet and spending fund from that, you need:
Seed A, Seed B, MPK C
or
Seed B, Seed C, MPK A
or
Seed A, Seed C, MPK B
(MPK = master public key)
Assuming you have 2-of-3 multisig wallet and you have the 3 seed phrases in different locations. It is kind of confusing me because to me it is still 2-of-3 multisig wallet in which only two seeds are need to make transaction, not three seeds. And also this setup to me is still 2-of-3, not 3-of-3.
I'd say:
try it (on testnet). Multisig is quite annoying to deal with for the first time, but by doing it you'll know how it's done.