What you have is two 1S3P saddle packs - in each saddle pack there are thee cells connected in parallel, and then the two 1S saddle packs are connected in series to make a 2S battery. You could change the wiring in each saddle pack from parallel to series configuration which would make two 3S1P 1700mAh packs, each would need a 3S balance cable added and be balance charged separately. Technically you can connect the packs in parallel to get 3S with 3400mAh capacity however this is somewhat dodgy as if they aren't both fully balanced charged to exactly the same voltage when you connect them together, a huge current will flow from more charged 3S pack to the less 3S charged pack, damage and fire may occur. Using each pack independently as a small 3S 1700mAh pack or connecting them in series as a 6S1P 1700mAh can be done without issue however.

The least dodgy 3S solution would be to make a permanent 3S2P pack which would require extra permanent connections between saddle packs since 1 cell in a saddle needs to be wired in parallel with one cell from the other. Would make more sense to make a new regular size casing or permanently bolt the two saddle casings together. Any time you connect 2 or more cells in parallel you need to make sure they are balanced before connecting them together with high current wiring. This can be accomplished with a balance charger or connecting them in parallel with a power resistor for some time before adding a direct connection.

If you have any doubt about what you're doing (which it sounds like you do) I'd recommend not attempting it and buying a premade 3S pack.