How to wire a single input for two separate chargers e-bike
The 5A and 10A you mention are battery side, correct? ... it makes sense with the 50 Ah.
Upstream on the AC mains the current will be lower, let's say no more than 5Arms.
Solution1. You can safely put a relay with rest position pointing to the 5A charger (lower=safer) and pushing a rocket switch (or a push button) you switch it to the 10A.
You need coil voltage for the relay. It can come from the 48V always present at the output of the chargers when the input is plugged into the mains.
Solution2. You can put directly a switch able to handle the 5Arms or so. There are some, no problem. Or for more safety you can put a 2-way model, with the two contacts in parallel.
Implementation2:

specs: 125Vac or 250Vac, and &gt;= 6Arms. Number of positions: at least 2 (for your 2 battery chargers, possibly a intermediate rest position).
selected devices: (C&amp;K CN series rocker switch) https://www.mouser.ch/datasheet/2/60/cn-1841876.pdf ; (Carling Tech. LRA series rocker switch) https://www.mouser.ch/datasheet/2/60/cn-1841876.pdf

Note2: the switch is in the position upstream you have drawn; C&amp;K has two contacts that can be put in parallel.
Question: what are those short pairs of marks on the left of the chargers? A symbol to say &quot;two wires&quot;?