Adding new drain into sewer line

I am installing a new water softener, originally planning to drain it into a nearby floor drain, which feeds into an ejector pit, which contains a sump pump feeding into a horizontal sewer drain. I have read recently, however, the salt water is not good for the pump. Instead, could I add a new drain onto this horizontal sewer line at the same point the sump pump joins it?

I expect it would look like this? Replace the elbow with a T (or sanitary T? or wye?) to connect the sump pump and also connect a standpipe with trap and airgap device.

Is this a good approach? Is there a better approach?

Thanks!

Other end of the horizontal sewer line from the sump pump and the larger line with all the other drains from the house.

Missed this until just now.

No, you should not attach anything else to the sump ejector line. The softener drain needs to tie into the main sewer line with an indirect connection, or drain into the laundry sink and go through the pump. I would drain it into the laundry sink.