Can I include text with contract clauses?

Yes. In MartialWave, you can register clause templates to be used within the contract, simply by creating each template in the Monthly Fees menu:

Once created, it can be chosen within the contract and edited to suit each occasion, without interfering with the template itself. You can also, if you wish, create it directly in the contract, simply by editing the field instead of choosing:

This text will appear in the generated contract PDF as it is registered. It is important to note that if a clause template is edited, this will not change the contracts already made with that chosen clause!