The difficult part of traveling with two backpacks is often the walk between transport connections. Two bags may be convenient once you reach your destination, yet awkward on stairs, through ticket barriers and while finding a seat. Decide how you will move with both bags before deciding where everything fits.
Start with the second bag's job
Separate an empty destination daypack from a loaded bag you must access during the journey. If the daypack is only needed after arrival, packing it inside the main backpack can simplify transfers. Lay it flat if the design permits, and keep rigid back panels in their normal shape. A packable bag may fold into its own pouch, but that does not make a structured laptop backpack suitable for the same treatment.
If the smaller bag carries a computer, documents or in-flight items, keep its contents limited to that job. Moving every dense object into the daypack can make the second bag disproportionately heavy. Consider which bag has the support and organization to carry each item well.
Compare three ways of moving
A main backpack on your back and a small bag held by its carry handle can work for a short transfer. It leaves one hand occupied, so think through tickets, doors and handrails. Switching hands does not solve an excessive total load.
Wearing a small backpack in front can keep both hands available, but check whether it obscures your view of steps, restricts your arms or prevents you from reaching the main bag's buckles. Practice taking it off without dropping either bag. If you cannot see or move comfortably, choose a different arrangement.
A compatible attachment system may combine the bags for part of a journey. Osprey, for example, identifies a specific Farpoint/Fairview Travel Daypack as compatible with the Fairview 40. That is evidence of one documented pairing, not permission to connect arbitrary backpacks by any convenient loop. Follow the instructions for the exact system.
Avoid making a swinging bundle
Do not rely on zipper pulls as attachment points for a loaded bag. Keep bottles, loose handles and trailing straps from swinging independently. The goal is a load you can put down and pick up predictably, not simply two objects that are connected.
If you do attach a smaller bag, verify that you can still reach the main opening and the straps you need to release. Look at how far the combined package extends behind you. Turn slowly in crowded spaces, and remove or reposition bags when the setting requires it.
Rehearse the transition you will actually make
Load both bags with the intended contents and walk around your home. Try a doorway, a chair and a step where you can do so comfortably. Put both bags down, retrieve a ticket or phone, then put them on again. This exercise reveals access problems that comparing liter capacities cannot.
Make a fixed set-down order so one bag does not disappear from your attention while you adjust the other. On boarding, separate the items that need different storage locations before reaching your seat. Keep the smaller bag's essentials accessible without needing to reopen the main pack.
Change the arrangement if the journey requires it
Carrying technique cannot remove the weight of a second backpack. If the setup remains cumbersome, reduce the contents, nest the smaller bag or reconsider whether a wheeled bag suits the route better. Choose based on your own ability to lift and manage the complete load.
Check the carrier's bag count, dimensions and weight rules separately. Attaching two bags for a station walk does not establish that they count as one piece of cabin baggage. The transport allowance and the physical carrying method answer different questions.
