You can add any custom data to your transaction and then decode it and use it in your own custom solution.
You can have a look at createrawtransaction for more information.
See @ https://www.multichain.com/developers/raw-transactions/
What type of transaction are you trying to achieve? Is it an issue of an asset or transferring an asset from one address to another? There are alternatives based on the answer to this question that involves not using createrawtransaction for example issuefrom and sendfrom. All 3 of the listed calls above have extra fields that you can supply custom data as you need it.