trasnfer data to same starting point

#1
In my dataset, I collected time-point measurements. I’m going to compare the changes in each group over time. But the problem is that the samples in each group ( although have normal distribution within each group) but has different median (or mean ) on time zero. I was wondering if there is any “statistically valid” method that I can transfer data in a way that all groups start with the same value on time zero?
 

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