There is no general answer to this question, it depends on the operator company and infrastructure available; the more visitors use the cable car, the more automated is its access system.
With some cable cars, you can simply present the Family Card to the ticket inspector and he/she will let your daughter pass.
However, many operators use nowadays turnstiles to restrict access; to enter you have to scan a ticket distributed by the operator; therefore, you might have to pass the ticket window first in order to obtain a free ticket for your daughter; with it, your daughter can pass the turnstile.
With some others you can scan the e-ticket distributed by SBB.
Simply ask the staff on-site how to proceed.