I have a related issue here: https://bitcointalk.org/index.php?topic=2049157.new#new
The difference is that the multi sigs were generated by Coinbase instead of Electrum. Maybe you can help? There is also a bounty.

Did you have Bitcoins stored in a Coinbase multi-sig vault as of June 26th, 2017?

If so, I can help you get free XLM from the Stellar Giveaway programme (https://www.stellar.org/lumens/bitcoin-lumen-program/)! Coinbase is marked as non supported on Stellar's website, but this is not true if you had your Bitcoins in a multi-sig vaults. It took me some time to figure out everything, but I now have ironed out the few steps you need to complete (the whole process takes only minutes for each address you control). It always works.

As of right now, each BTC you held is worth about $17, that you can immediately cash out if you want. Stellar's giveway will end on August 27, 2017, so better hurry.

Just send me a MP and I'll answer you with a FREE complete guide (I'll of course appreciate any reward if it has worked for you .

Do you know where I can find their usernames? Thanks for your help!

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