Subnetting question

Hi all,

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Networking is not my strongest area...

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We have 3 branches

Branch A = 172.16.2.0/23

Branch B = 172.16.4.0/24

Branch C = 172.16.6.0/23

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In branch C I would like to create new subnets (172.16.8.0/24 & 172.16.9.0/24)

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What is the best option for this? I first looked at just making Branch C 172.16.6.0/22 but that makes the range 172.16.4.0-172.16.7.255 and I can't do that as Branch B overlaps.

So I thought maybe just add 2 new /24 subnets as mentioned above but I am just stuck, not sure it would even work. I've played around in my router at adding a new LAN but not wanting to disrupt the live network. My router is a Draytek, under the LAN profile there is a section called More Subnet. I added 172.16.8.0/24 in this and statically assigned a laptop with this and i could ping from the laptop to Branch C but not Branch C to laptop.

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I'm way over my head right now, everything I have learnt years ago has disappeared and I'm feeling pretty low I can't work out something that shouldn't be too hard I don't think?!

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Thank you for any advice.

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