How can I and my daughter apply for dependent visas in Thailand after my husband's visa extension?

Please, explain who knows...

If my husband make visa extension based on 50 y.o and me and our 14y.o. daughter want to make depends. Our steps are:

1. All of us can arrive to Thailand with stamp of arrival for 30 days (russian passports).

2. Not later than 1 week, my husband go to immigration on Phuket to make an application (money requirements we know).

3. He receives the extension for 3 months.

4. Me and daughter going to KL or Pennang with copy of husband's passport and receive dependant visa for... 3 month? Or till the end of his?

5. After 3 months we are going all together to phuket immigration and make extension for 1 year.

Am I right? Before I thought that we all can make application here the same time, but few days ago we was in immigration and the man, who helps visitors there in information corner, told us that only husband can make extension here. We can not... And gave us this