「外国人登録をする時もいっしょについて」 Why ついて?


I am confused by this sentence in my textbook and I hope somebody will help
me.

> (talking about the host family, specifically the mother/wife)  
>  外国人登録をする時もいっしょについて来てくれました

I think this is saying the wife in the host family helped with the alien
registration. But the pattern does not translate well to me.

> At the time of doing the alien registration, together we...

Then I think it is strange because について is to highlight the subject, and
then...

> 来てくれました

I appreciated her coming?

I would say:

> 外国人登録をする時は お母さんといっしょに会社に行きました。助けてよかったです。

but perhaps this describes a different situation. Perhaps she met him at the
office to do alien registration.

Could somebody break down the textbook sentence please? I am finding it uses
odd patterns to me.




It's not as easy to tell in the original sentence since `ついて` is written in
hiragana, but `付いて来る` is a phrase meaning "to accompany".

> 外国人登録をする時もいっしょに付いて来てくれました  
> (My host mother) accompanied me to the alien registration.

The `くれました` is the `-てくれる` pattern which means "to do the favour of doing X".
It essentially indicates that this is a favour that they did for you and that
you appreciate it (much to the same effect as the `助けてよかったです` in your version
of the translation, but nicely packed into one sentence), and also helps to
imply that the subject/topic of the sentence is you, the speaker.

