`--sequence` for multisig

Someone can explain me how multisig signing and broadcast works? I did it multiple times, but sometimes it gets completely stuck, even adjusting gas limits it doesn't help.
I wonder what sequence in signed tx is? Like:

```json
{
"signatures": [
{
"public_key": { "@type": "/cosmos.crypto.secp256k1.PubKey", "key": "..." },
"data": { "single": { "mode": "SIGN_MODE_LEGACY_AMINO_JSON", "signature": "...." } },
"sequence": "6"
}
]
}
```

So here it is sequence 6, if I create another offline tx and sign it, it gets sequence 7. When broadcasting it, it just hangs. So if sequence is the reason. How do I delete an older sequence?

@DariuszDepta

The issue names no files, tests, or entry points. Start by investigating the multisig signing and broadcast flow described in the issue, including the meaning of the signed transaction sequence and why a later offline transaction can remain stuck. Done means documenting the sequence behavior and the relevant resolution for this broadcast scenario.

Written by the indexing model from the issue text.