Combining fake lashes with eyelash extensions isn't advisable due to potential strain on natural lashes and the risk of weakening the extension bond. The added weight and adhesive from the fake lashes could cause premature shedding and compromise the overall health of your lashes. It's crucial to prioritize the care and maintenance of your eyelash extensions to ensure they last longer and look their best. Consulting with a lash technician for guidance tailored to your needs is always a good idea.