I have a window/sliding door that goes out onto the balcony in my unit. The length is 420cm. I am looking to install a new set of curtains. The existing rod was installed by the previous owner. She has used 4x 1~m rods with 5 brackets. 2 brackets on each end, 1 in the middle and 2 half way on each side. If put my new curtains on the existing rail they wont be able to slide all the way because the existing brackets are quite thick. I am not sure C rings will go round them.
I wanted to install a new rod using these windoware rods from bunnings
There is no specific joiner for that style of curtain rod. I can suggest removing the end pommels and joining the two lengths with an Everhang M10 x 100mm Zinc Plated Dowel Screw. You can then use a single Windoware 33mm Walnut Wood Pole Bracket in the centre over that join. If the curtains you are using are not very heavy, this method should be fine. However, if they are heavy woollen curtains, there is going to be a lot of weight on that central hanger, and you'd want to screw it directly into a timber stud instead of the plasterboard.