Charge Source Priority setting

First my concept and system:
12 PV panels 3s3p and 3s, total 4kW nominal. 2 Synergj/Axpert MKS5K off grid inverters in parallel, 4x LiFePo 48100 packs in parallel.

The concept is to become as much as possible independent from the grid. The size of the system is based on years of electricity consumption records, witch resulted in an average daily consumption of around 10kWh (2 person household, electric cooking, electric geyser with additional 2m² heating panels). My aim is to harvest as much solar energy as possible. The other issue is to make sure that at any time I have enough SOC left to cover an eventual load shedding. UPS is the second function of the system.
Therefor I set charge source priority to "solar first, utility charging only if solar is not available". On Voltronic inverters it's setting 16 to CSO. "Back to utility" (12) to 48V, "back to battery" (13) to 50V. That worked fine until we got visits that stay longer, the house is overcrowded, the solar system overwhelmed. The system frequently needs complementary energy from the grid. I noticed that during morning and evening hours and during cloudy days the recharging in utility bypass mode takes long since the sun is weak. During all that time the household consumes from utility. So as a trial I set (16) to SNU, "Solar and utility charge at same time". As far I observed that works fine. If in utility bypass mode with weak sun it recharges from utility and from the PVs as well. The utility charge current limit is set to C 0.1. No solar energy gets lost. The recharging time until switching back to battery is far shorter. In battery mode there is no charging from utility anyway. I had to change that setting on each inverter individually, as it is not synchronized in parallel setting.