How to parse first line in all the next lines

Hello everyone,

I am having the following log :

Sun Dec 20 00:40:05 CST 2020: Starting docker, stream=prod, version=latest, pwd=PATH
Processing...
SERVER oc: Successfully processed 23 TSM servers. Failed: 23
Details:
1 (Host1): HTTP POST request failed, rc=500, null, msg=Internal Server Error
2 (Host2): TSM Server registration not found for hostname Host2
3 (Host3): HTTP POST request failed, rc=500, null, msg=Internal Server Error
4 (Host4): Index: 0, Size: 0
5 (Host5): TSM Server registration not found for hostname Host5
6 (Host6): HTTP POST request failed, rc=500, null, msg=Internal Server Error
7 (Host7): TSM Server registration not found for hostname Host7

Processing completed, elapsed time=896.59 seconds
Sun Dec 20 00:55:05 CST 2020: Finished, rc=0

I need that somehow filebeats read just the events that start with a number but adds the first line of date to each one of them, for example:

Sun Dec 20 00:40:05 CST 2020: Starting docker, stream=prod, version=latest, pwd=PATH 1 (Host1): HTTP POST request failed, rc=500, null, msg=Internal Server Error

Sun Dec 20 00:40:05 CST 2020: Starting docker, stream=prod, version=latest, pwd=PATH 2 (Host2): TSM Server registration not found for hostname Host2

This since I need to extract every host event but with a date associated to it.

Can you Help me please?

Thank you

Regards

Kevin Scott Urbina Moreira