Quote
18 txn: mempool-conflict
This error indicates that one or more of the UTXOs that you are attempting to spend in your transaction has already been used in a transaction that was already broadcast.In other words, your transaction is being rejected as an attempted "double spend".
That's what I was afraid of.
The problem with coinb.in is that you can not copy paste every transaction in the outputs part.
Because maybe one of those has already been spend and I need to press minus next to that?
But how can I find out which one that is?
The multisig wallet required xpub or something private keys, which coind.in does not supply 
So I can't import this wallet into Electrum
coinb.in supports creating/signing transaction with multisig address So I can't import this wallet into Electrum
first, you need Redeem Script to retrieve utxo from multisig address
then at signing you need to do it twice (if 2 of 3) consecutively with each privkey
unsigned rawtx + privkey1 = partially-signed rawtx
partially-signed rawtx + privkey2 = multi-signed rawtx
but HCP has explained, mempool-conflict = attempted "double spend"
@OP if you are still in doubt, check your multisig address balance on any explorer
or tell us the address, so we can check and give advice on the matter
I have the redeem script. Then I have 3 private addresses of which one is the same (for the Legacy one instead of the Segwit one).
One of those addresses is AES. I don't have any more private addresses than that.
So I can only do this:
unsigned rawtx + privkey1 = partially-signed rawtx
I need to do this 2-3 times? Why? That doesn't change anything does it?
I will check my multisig address and let you know.