fiscal partner status for unmarried

Good afternoon.
I-KM, my girlfriend came as my partner, which is written in her permit.
We have been registered at the same address for more than 6 months and want to obtain fiscal partners status in order to receive a tax deduction for a non-working partner.
I read that to obtain this status, in addition to registration for 6+ months, you need to fulfill at least one more of a number of criteria (marriage, joint children, etc.) Of all these criteria, only confirmation from the pension fund that she is registered there is suitable for us as a partner in a pension plan, but the BeFrank company does not provide such paper, citing the fact that for them a partner is someone who has been registered for more than 6 months together.
The question is - where to contact the tax office and what to provide them (there are emails from BeFrank stating that this is their approach) in order to still get fiscal partners?
Thank you!