Needing advice/lost on where to go

So in the last year I started dating a wonderful couple. About 6 months in they asked me to marry them and a few months later I moved in. We just hit one year and everything is going well and we’re about to move in to a new place together. We have 4 daughters that get along for the most part except recently the older 2 have been acting out a lot. We’ve chalked most of it up to the fact that there’s been a lot of change and they’re feeling like they have no control. We understand and are trying to be understanding but it’s getting out of our control of being able to handle the situation. The 9 year old decided a few weeks ago to steal from the school fundraiser to buy snacks (instead of the ones we have at home because she didn’t want those) and has been caught lying about any and everything she can try to get away with, won’t do her chores, won’t do what we ask of her without a fight, etc… the 7 year old has also had a lot of issues with lying about any and everything and yesterday after having an entire day about her where she got to go to the store, but a toy, and pick out what we were having for dinner decided she wanted some candy. When she was told no because she had gummy bears at home and didn’t need anymore candy she decided to steal it and then gaslight her mom telling her the rustling of the candy wrapper she had heard must have been a bag she (mom) rustled with her arm. We have tried everything with the girls. Grounding. Stern talking to. Trying to come at them like they’re more mature and reason with them about it. But it seems like the more we talk to them the worse they get. I’m worried about what will happen next. They already destroy the place we currently live and don’t care I’m afraid of what they’ll do to the new place after we move. Any advice would be great