There is one stock overview — the physical truth in the warehouse. What each channel is allowed to sell from it is a separate, deliberate decision. Publishing the same raw number everywhere is what turns a synchronisation problem into cancellations.
BizBloqs holds that single authoritative position and orchestrates what goes outward per channel. Amazon and Bol punish out-of-stock hardest, so they get their own safety stock, buffer and availability strategy; your own webshop can run leaner because the commercial risk of a stockout is yours to carry.
Strategies are rules, not spreadsheets: safety stock per channel, allocation ceilings for campaigns, priority order when stock gets tight, minimum cover before a listing is throttled, and separate treatment for pre-orders and back-orders. Reservations land the second an order does, so every channel's published number already reflects it.