I'll chime in on this but want to clarify terms as it's a wee off. Battery "Pack" is a complete battery with X # of cells & it's own BMS. Battery Bank is multiple packs set up as a bank. As I understand your description, you have 4 Battery Packs, each with BMS set in Parallel to make up one bank of batteries. Orion BMS is Top Quality stuff but it is not a Distributed BMS (Think Batrium $$). Even with a distributed BMS, it would have to allow the packs to disconnect independently for Hi/Low Volt or Out of Temp Range conditions while keeping the whole bank running down to the "Last Pack Standing" at which point it could tell Charger to shut down or cut loads out, depending on the situation.
Ideally, each pack should be set up so it should be capable of being the "Last Man Standing" by handling the full Discharge or Charge expected from the system. You can never to certain that all packs will remain connected and don't want to be left in a lurch. The packs should be programmed identically for cutoff points, limits, capable of handling the amps in/out etc.
Chargers are Constant Current / Constant Voltage, it should be capable of reading the amperage, as the packs fill-up the resistance will change to the point they will no longer accept voltage. By that point in time eh BMS should be ready to cutoff. The tricky part is that not all packs will reach that point at the same time because every cells is slightly different and so the "pack" as a whole may vary a bit between each other. If you are using Premium Matched & Batched / Binned cells this is less likely to occur but with the usual Commodity Cells we are using like the EVE-280's (even the Bulk Calbs) will deviate and diverge a bit, on average up to 1mv per AH of capacity, so a 100AH cell can diverge by 100mv and that is not unusual. But the end result is that can make the pack's thresholds vary a bit. The ideal is that the Charger should push as many amps it can or up to 0.5C as that is what makes these LFP's happiest, even though they can take 1C (that heats them up and can cause expansion). The Bank Collectively will absorb all of that until resistance starts to lower the amps being taken in, then as the packs hit Full and the BMS' cuts off, the remaining charge receivers get more and top off and cut, the last pack standing will drop amps to the point of a trickle by which time the charger should shut down.
THE BUGABOO !
The Charger MUST be a good Smart Charger designed for LFP Support. Chargers for Lead, AGM etc are not suitable. Being able to read Amps and have End Amps Monitoring (and preferably configurable). Why configurable ? at 100% Full 3.65V the accepted amp input will be low but not so at 90%, as the resistance won't be there "yet" so if you can program the end amps you can note the amps accepted at 90% and then program the Charger to cut off at that threshold. Most good Solar Controllers use can End Amps as well as many higher-end Inverter/Chargers.
Packs in Parallel will share Load & Charge, they also in a sense balance voltage across the packs in the bank as they are on the common DC Bus. The Common DC Bus for the Packs making up the Bank is quite critical to get right because if done improperly can lead to errors and potential imbalances. I'm sure you've seen it but I'll post this doc from Victron which is great at explaining the parallel pack setup (starting page 17)
VICTRON Wiring-Unlimited-EN.pdf
Here is an Excellent write-up from Norkyn Marine as part of their larger series of docs: (There is much more on their site)
Key considerations in the protection and management of lithium battery banks.
nordkyndesign.com
And of Course the "Marine How To":
https://marinehowto.com/lifepo4-batteries-on-boats/
Hope it helps, Good Luck.