How to connect two S7-1500 controllers to S7-410 using profinet?
What possible architectures and possibilities do we have in PCS7 to realise this?

It's very possible, but the solution depends significantly on the overall architecture.

If both controllers are simplex, you can use the 1500 as idevice and put it on the 410 PN network as a slave.  Or you can use a PN/PN coupler and data exchange through that.

410H and/or 1500R/H your best bet it so use a PN/PN coupler potentitally in combination with Y-switch if R1 PROFINET.

A combination of H and simplex could be a blend of solutions.  It's quite specific.

Also you don't even need to use PROFINET, you can just do Industrial Ethernet messaging for example using the Industry Library.  There are many options.