Extending system models

Hi,

Is it possible to extend core system files? I need to add extra functions for customers to perform specific checks and in 1.5 I have added these directly to the customer model but would like to avoid modifying core system files - where possible!

Is there a better solution? I have looked briefly as Override Engine but it seems a little clunky!

Any advice would be appreciated!

Thanks,
Rob

Use the override engine from the marketplace or VQMod.