Hi @kathrynw,
Many thanks for your question and welcome to the Bunnings Workshop community, it is fantastic to have you join us.
The Flexi storage drawer runners are not designed to be retro-fitted with a soft close option from a third-party. However, it could be possible to upgrade the Flexi Home Storage & Wardrobes to include soft close runners, but you would have to confirm the dimensions of a suitable replacement
I'd suggest taking the drawer slides from the Flexi wardrobe unit and comparing them with some Goliath Soft Close Drawer Slides. If the sizes match up well, it should be just a case of swapping them over.
The main thing I would be comparing is the thickness. If they are wider than the ones that come with the wardrobes, they will rub and won't run effectively.
You might like to check out How To Install Drawer Runners for some guidance.
Let me know if you have any further questions.
Jacob
