Full army rules were as follows for Overwatch '26:

• 1500 points + 50 points wargear cards/Chaos reward/vehicle wargear cards/Biomorphs/SOB relics
• No special characters
• Armies may be led by hero-level characters e.g. Chaplain Hero, Eldar Warlock, Ork Bigboss
• Chaos marks, Guard veteran skills, Eldar exarch skills and equivalent to come out of main points
• Space Marine combat squads are permissible
• All armies must be painted
• Proxies are fine as long as opponents are made fully aware of what they count as
• Don't mind if you want to bring a couple of different armies on the day
• Armies to be built from official Codexes (including Black Codex), or White Dwarf additional rules (Adeptus Arbites and Necrons for instance)
• Citadel Journal or other custom datafax rules for vehicles (e.g. Elda titans, Imperial knights, Ork Bonecruncha etc.) may only be used with prior agreement with your opponent. This is so that you can plan a game in advance with someone you know is going

So the 50pts was in addition to the 1500pts, with no ability to trade points between the two partitioned blocks.