Accessing remote IPSec via another IPSec tunnel

[OpnSense_Learner]

Hello all,

First post and very much still learning OpnSense! All help appreciated.

Site A - Primary office, and where OpnSense resides.
Site B - remote office, running Unifi - IPSec Site to Site VPN in place

Additionally, a number of further sites are connected to Site A via IPSec tunnels.

Is it technically possible to access the sites connected to Site A, via Site B? E.g. can one IPSec tunnel access the IP address ranges delivered via another IPSec tunnel? If so, what considerations needs to be made?

I've been running some tests and although I suspect some Unifi configuration to be the issue, I want to make sure the above is technically possible!

I would be happy to answer any questions for further information.

Thanks