SImagic is horrendous. AVOID. I had a similar issue in the past in relation to business. I needed to access both personal calls/business calls on the same line and it was a nightmare. Dual sim phones are very rare and they don't come out in the market as often as standard phones.
There was a service I used in the past which would provide a "redirection / forwarding" service. However, it would only work with texts. You would be able to text as "Unknown" but when they reply, it gets forwarded to your "virtual" number which in turn gets forwarded to your original number (so at the end of the day, they don't see your real number).
But that was also a nightmare and it had several downsides/issues so I ended up just buying a second cheap phone that can take calls etc for around £40.
I think that's probably the most convenient option.