my daughter need to switch to a new account is there any awy she can do it without having to ...

Nothing can be transferred between accounts.

why does your daughter need another account ? Someone brothering her it's simple to fix set privacy to friends only

If it's because she's an child account trust me after hearing so many horror stories of kids abusing their parents cards on adult accounts I wouldn't recommend allowing your child unrestricted access

1. If your daughters Xbox is set as your son's Home Console, then she would be able to install and play it without any issue and without needing him to sign in. The question back would be do they EACH have Xbox Live Gold or only one account? Xbox Live
Gold allows them to play online, and if your son has it, the Home Console designation would allow your daughter to use it as well. If they both have it, then it's no different or issue.

2. If she signs in on the Xbox One X, she can install them directly, or use Network Transfer to copy them over the
local network, which would likely be faster. If she's on the One X signed in, then her progress and saves will sync and she can pick up where she left off, and it should be seamless.

3. Each account can only have one Xbox set as Home Console, and each console can only have one account that claims it as "Home Console". It's a one to one relationship there, so each console has a different account set as home. My recommendation would
be:

Xbox One X, son's primary console -> Set as Daughter's Home Console

Xbox One, daughters primary console -> Set as Son's Home Console

That way they both have access to all of their and their siblings games by default. This is a similar setup to what I use at home for my son, daughter, and myself. I just throw a PC into the mix as well to play Minecraft and Sea of Thieves with them.

Please do not hesitate if you have any more questions.

Yeah, I know you were trying to prove a point, but my wife actually will love the X1. She already likes what Kinect can do on 360 to control Netflix and so forth, so I know she's gonna be f'ing psyched when she finds out she can tell the Xbox to turn on,
switch to live tv, and tell the Xbox to search for 'Real Housewives' without having to search all over for the remote which is perpetually left in bizarre places by our daughter.....

there are several factors involved to choosing the best options for setting the Home Xbox.

1; how many people play on each one

2; which account purchased digital games and/or Live Gold and/or Game Pass

if it is only your Daughter that uses the Xbox then all she needs to do is sign in and she can play her games even if the Xbox isn't the Home Xbox.

if you use the Xbox and games, Live Gold and/or Game Pass are on your account then you would want to make the Xbox at your Daughter's Grandmother's the Home Xbox for your account, then when your Daughter is at home, you would need to sign in to the Xbox
then switch profile by pressing the Xbox button then pressing LB 4 times to get to the sign in tab, then select your Daughter's account and she will have access to the games and services.

if other people use the Xbox at your home and the games/Live Gold/Game Pass are on your Daughter's account, she sets the Xbox at yours as her Home Xbox and then she'll have access to games and services at both places and you will have access on the Xbox
at yours.

hope this helps