DSM 400

[Boatzguy]

Hi, I just spent a couple of hours on the phone with Raymarine support, elevated to level 2, and was told my DSM 400 sounder will not talk with my e165 MFD. This is a new boat to me, old owner says they worked together previously. Is this an absolute answer, no way to get these two kids to talk with each other? Is there any way to get just depth info to the MFD by adding a legacy fishfinder, then getting depth info to the MFD through the seatalk HS, or the seatalk NG?
System is e165 MFD with SeaTalk HS and SeaTalk NG inputs, 4kw HD radar to MFD via SeaTalk HS switch, RayStar GPS to MFD via SeaTalk NG, and DSM 400 is connected to the SeaTalk HS switch.
If this DSM 400 just won't talk to the e165, is there a newer sonar that will use the transducer (Airmar SS270w, 50kHz and 200kHz) I have installed? Thank you for any help or ideas to get my MFD to show the depth, I'm not a real fisherman, just want depth information.