Your take off is from Abottbad so you can just go to Hunza very very easily given you exit trafic of mansehra in early morning and camp at Duikar/Eagles Nest as mornings at eagles nest are more refreshing then a I have ever epsrienced.
Nex day you can take ur probox to Khunjrab Border. and come back to same camp in Hunza and sleep.
3rd day you can come back to abotbad home just as you went.
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The above plan is only for Visiting Khunjerab pass, if you havne tdone sight seeing ahead of Riakot then the itenray would be totally different.