Based on your information, I assume that you currently hold a permission to reside (Aufenthaltsgestattung) with the employment permit for your current work. Furthermore, you have filed an appeal at the Administrative Court against the Federal Office's decision of refusal. If my assumption is correct, it is incomprehensible why the immigration authority requires the passport from you. As long as the appeal has suspensive effect and as a result you are not (yet) enforceably obliged to leave the country, you are not obliged to cooperate in efforts to obtain the identity paper.
Something else would apply if your appeal doesn´t have suspensive effect and you only have the temporary suspension of deportation (Duldung). In this case, you´re obliged to cooperate in efforts to obtain the identity papers including passport.
Regardless of this, it should be noted that the permission to reside and the temporary suspension of deportation are generally only issued for a maximum of 6 months. You will not be able to obtain an extension of those documents for 15 months, as required by the DHWB, from the immigration authority.
For lack of further information, I can´t check whether or not you meet the requirements for the residence permit for well-integrated foreigners whose deportation has been suspended in accordance to section 25b Act on the Residence. Because of this, you should contact an advice Center at your place of residence.