Hi,
If the ISPs are common on both sites, you could announce separate /25 with no-export community or both /25s with different MED + no-export and the aggregate /24 as default. This would allow routing of the 2x /25 prefixes within the ISP ASN to different eBGP neighbors, i.e site A & B, if the ISP is agreeable.
As per diagram, if route for only 1x /25 is present on one site edge routers and no next-hop available for /24 aggregate, this could result in blackholing the other part of the /25 at that site.
Cheers,
Ashvin