alright so you have 2- 2awg wires running into 1- 2awg wire. You need to fuse both of the two wires running from the battery(protects against a short which could cause a fire in either wire) as close to the battery as possible, with fuses that are rated within the current carrying capacity of the wires( a 15 foot length of 2awg(note: awg rated, not just #2) can carry about 200 amps safely). Therefore, fuses that are 200 amps or less are fine. Now you also need to fuse at the distribution point for the single wire as a short in that wire will pull more current than a single 2awg can handle(causing a fire) being supplied by 2-2awg wires. In other words, if the single 2awg shorts, it may not blow both of the 200 amp fuses before it catches on fire. Another option is; You could fuse the 2 -2awg wires at less than a 100 amps each to be safe, which will protect all the wires. Personally, I like the first option as it's a double safe system, just incase your fuse(s) don't blow early enough. Hope that helps.

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2004 300M SPECIAL
Alpine CDA 9833
Alpine Pxa-h701
Alpine Rux-c701
Rockford fosgate p400-4
Rockford fosgate p4004
Hifonics BX 1205D
JBL c608 GTi
JBL p963
Infinity 2.5" center channel
Alpine type R 12"(2)
200 amp alternator
yellow top battery
0 awg power and ground (welding cable) 300 amp anl fuse
all active SQL set up with 2000 watts rms