How will I make recording into the flash and fms4

You can record and multicast by publishing to the server and recording as you would for RTMP unicast, and then republish the stream to the netgroup using netconnection and netstream on the server side. See the section on "Publish a stream to an RTMFP group in the docs:

http://help.adobe.com/en_US/flashmediaserver/ssaslr/WS5b3ccc516d4fbf351e63e3d11a11aff5ba-7d13.html#WS5b3ccc516d4fbf351e63e3d11a11afc95e-7fd6

I imagine you can also use the server side Stream class to subscribe to a netstream being published to the rtmfp group by a client, but I haven't tried that myself, so I'm not sure how well it would work. That said, if you want to be sure the recording isn't missing any video data, taking this approach might not be a great idea (lost video data on the UDP stream would mean lost video data in the recording)

Keep in mind that RTMFP multicast is not available in FMIS4. It's only available in the developer edition (limit of 50 peers, limit of 10 minutes of multicast streaming), and in the enterprise edition (unlimited peers). The enterprise edition is very expensive (many times the price of FMIS4), so I'd suggest getting a quote from adobe sales before making recommendations to your client.