3 of my grandchildren, ages 5,13,16 are medicated for ADHD. The 16 yo takes quanfacine. The 13 and 16 yo also take a form of amphetamine salts. Ritalin and Adderal are amphetamine salts. They tried different combinations and different formulations of amphetamine until they found what works. Sounds like the guanficine is working for your daughter.
My daughter dealt with meltdowns separate from medication.Just as with typical children you treat meltdowns in a way that works for each child. If you're not getting professional help to learn what to expect and how to manage, I behaviour for your child I urge you to do so now. Read about child development and ways to discipline. Take a parenting class that incudes ADHD issues if you can find one. One to one counseling may help. Work with her teacher and school counselor. If she doesn't have meltdowns at school, learning her classroom structure may help.
What issues cause the meltdowns. How does she act in a meltdown? What is your response to a meltdown? What can you do to reduce meltdowns?
If she has temper tantrums, completely ignore her. If she cries, respond with love, without trying to talk her out of the way she feels. Help her to use her words.Keep your involvement brief. Often parents want to fix how the child feels and the reason she is crying or being angry. That is impossible. Focus on preventing the behaviour. If she wants a hug or to be held do that, without talking except to mirror her feelings. "I see you you're upset. I'm here for you. You can calm yourself down." Above all, never give in to what she wants or doesn't want. Help her use words such as I'm angry because I want to do such and such. Soothingly tell her she can't, or has to do such and such. Give her an alternative. "When you stop crying, I'll help you put your toys away." "You must go to school now. I'll see you tonight." Don't linger at drop off.
My 3 and 5 yo daughter's have frequent meltdowns. For the first few years their dad would hold them and try to soothe them. Now he says, "stop that. It's You're OK." He's more and more letting them work it out by making suggestions. Meltdowns are shorter. Girls move on to something else. Sometimes with Dad's help. Sometimes on their own.
The 3 yo often has a crying meltdown when I leave. I distract her by asking her to open the door for me and push the elevator button. The elevator is just a few steps away. Another thing her dad does is to help her get involved doing something she likes. She soon forgets that I'm leaving. When the 13 yo has an angry meltdown, parents ignore him and talk with him later.
Perhaps your daughter has meltdowns because she has sensory issues. My 5 yo and 13 yo have sensory issues. They often have difficulty with noise. Both of them have learned to go to their room and shut the door. The 5yo gets angry, slams the door and yells go away. We leave her alone. She eventually calms down.
Kids have meltdowns when they're hungry or tired. Treat/ prevent meltdowns by feeding them and seeing they get enough rest/sleep.
I'm just guessing on what kinds of melt downs she may be having.
Yes kids grow out of meltdowns when they are helped to learn to use their words and ways to help child learn coping skills, parents anticipate, and learn how to head them off, and don't reward the meltdown by giving the child too much attention. Be briefly sympathetic and move on.
Without knowing why your daughter has meltdowns and how she acts, I may not be addressing your needs.
I do think maturity helps reduce meltdowns. The 13 yo and 16 yo don't have meltdowns. They do get angry and need skills to deal with their feelings.
We've recently had a couple of questions about meltdowns. The posts have not mentioned ADD or ADHD. Kids without those conditions also have meltdowns. I think in one post the child was 5 or 6.