Switch to bridge from routing?

I have multiable sites which I am routing.

On our roof we have a 802.11b hotspot/ppoe interface, and a 802.11a station shooting to the mountain.

On the mountain is a 802.11a station at the mountain with a 802.11b hotspot/pppoe interfaces.

I want to add many more relays (4-5)

Do i just keep shooting 802.11a backbone to each radio and then route to each 802.11b?

Or do I go with wds? If I go with wds do I no longer need the 802.11a links for backbone on each relay point?

What if I added a 3rd or forth station using wds but they can not see the wds station on our roof?

Regards,
Michael