Buenos agrees with suegros, not with each individual person:
Even if the actual people are one man and one woman, a mixed group takes masculine plural in Spanish:
Likewise:
Here ser is used because we’re describing their character / usual way of behaving, not a temporary state.
So:
In Spanish, when you mean “to be good/kind to someone”, the usual pattern is:
So:
Mis suegros son muy buenos conmigo.
= My in‑laws are very good / kind to me.
Other prepositions change the meaning:
If you want to avoid conmigo, you can also say:
So:
You could say:
Yes, but the version in your sentence is the most natural:
Other possible orders (usually for emphasis or style):
Conmigo, mis suegros son muy buenos.
(Strong emphasis on “with me” → “As for me, my in‑laws are very good.”)
Mis suegros, conmigo, son muy buenos.
(More written or rhetorical, with commas as spoken pauses.)
But in everyday speech, the original word order is by far the most common.
Yes, a nuance difference:
Me tratan muy bien.
In many contexts you can use either, but ser bueno con alguien is slightly more about what kind of people they are towards you, and tratar bien a alguien is about their behavior / treatment.
Suegros is completely neutral and widely used in all registers in Spain:
You might sometimes hear joking or informal alternatives like:
But suegros is the standard and safest word.
Just change conmigo to the appropriate prepositional pronoun:
Note: only mí (with accent) + con → conmigo is irregular. The others are regular con + pronoun.
Yes, some natural alternatives in Peninsular Spanish:
All of these sound natural in Spain, with majos being particularly colloquial and common.