Can I petition them if I only have a conditional residency?

You can file petitions for your daughters. The problem is that filing of a petition does not extend their visas and does not give your daughters the right to remain in the U.S. while they wait for the green cards. If your daughters are under 21 years of age and not married, their green cards will become available in 22 months (it will take a couple of months more to actually receive them); if they are over 21 and not married, the wait time is 6.5 years (unless they are citizens of the Philippines (wait time - 10.5 years) or Mexico (wait time - 21 years). If your daughters stay in the U.S. after their visa status expires, they will not receive green cards at the end of the waiting period: they will be required to leave the U.S. for 10 years. If there is a reason why they cannot go back to their country, you need to speak about it with an immigration attorney. There is also another reason for a consultation: depending on the details of your case, it might be possible to avoid the petition process altogether and obtain green cards for your daughters in a few months, possibly, without the need for them to go back home.