You can use the "Paste over" function in the Edit menu to replace all the timings in a file, with those from other subtitle lines you have copied from a timings file.
So you would:
1. Open your timings file
2. Select all lines (Subtitle menu, bottom-most item)
3. Copy them (Edit menu)
4. Open your target file
5. Make sure the first line is selected
6. Use Paste Over (Edit menu) and choose just Start and End times
Do not PM me asking for help with Aegisub, Automation, karaoke or anything like that, I won't reply.
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All rights reserved to call you insults if you ask poorly thought out or redundant questions.
Experimenting is free and is a great way to learn things.