Obtaining a passport without consent of the other parent

My husband and I planning to go overseas later his year with his daughter. She has not seen her biological mother for 8 years after she walked out of her life (after a turbulent relationship with him over jealousy of my role etc). My step daughter's passport expires next month and so she needs another one for our next trip. My husband's ex has decided to blackmail us with the passport app saying she will only sign it if we take SD over to say thankyou (I'm thinking "thankyou for not being in my life for the last 8 yrs!) She has cleverly worded her letter to say that she is more than happy to do mediation (something she refused to do 8yrs ago) because she knows we can't obtain a passport without consent unless we have 'exhausted all avenues (including mediation).'
I am wondering if anyone else has had a similar experience?
Can we be black mailed in to doing this?
What rights does a 15yr old have? She said she doesnt want anything to do with her but is now being forced to...
Grrrrr:wall:

no idea but wanted to send you hugs

There is a section at the bottom of the form in relation to children who haven't seen their other parent for a significant period of time. Check with the relevant gvt dot.

Thanks for the support guys. This has me really angry! Why should we be stopped from going overseas just because she feels like being a cow. Grrrr

My sister just went through the smae and as it takes longer if it dosnt have both parents sign she had to get her ex to sign. She did find out that in certain cases you dont have to get both signatures

In the case of my ex, a passport was declined for his son (who he had no seen in years) because my ex declined permission.

You might find that because its a passport renewal, rather than a brand new passport application, that you don't have as big an issue. Don't wait until it has actually expired though because that might complicate things further.