BIP125 is the standard way to signal:
https://github.com/bitcoin/bips/blob/master/bip-0125.mediawiki

Should explain everything you need.

On Thu, Jan 12, 2017 at 9:02 AM, Police Terror via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> Hello,
>
> Where can I find the rules on transaction replacement?
>
> For instance what are the valid ranges for the sequence values in
> transaction inputs? Normally I set this value to MAX_UINT32, and the
> locktime to 0.
>
> Can I change the outputs? Can I add more inputs to pay a higher fee?
>
> Just looking for clarity on this aspect of Bitcoin. Any resources would
> be much appreciated.
>
> Thanks.
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