If the quotes are accurate in this article than I would disagree that there is not enough information here. Of course if it’s incorrect than perhaps a “welcome” is not being offered for bringing a “partner into the family”.
The description here is not of welcoming their son and another person but their son and his “partner”. That distinction makes this not like welcoming any other person. I think children would note this very closely.
“...welcoming their son and partner to the family” is, in the contemporary use of the word “welcome”, acceptance of the relationship.
Acceptance of an ongoing homosexual relationship is de facto approval, and the grandkids will notice the approval.
Acceptance of the son and his partner as sinners? Definitely, for as sinners we all need acceptance, but we must be repentant sinners. The grace is given to us sinners so that we repent.
Acceptance of the son and his partner as ongoing homosexual lovers?
I CORINTHIANS 6:9-11:
9 Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived; neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor homosexuals, 10 nor thieves, nor the covetous, nor drunkards, nor revilers, nor swindlers, will inherit the kingdom of God. 11 Such were some of you; but you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus Christ and in the Spirit of our God.
If they're welcoming a "partner nto the family," they are conbtributing toi moral corruption.
If they are welcoming thier erring son and his friend for the purpose of maintaining a trust-relationship -- needed in order to make truth-tellng possible ("we love you, but what you're doing is way wrong, you're sabotaging your own lives and offending God")--- then they're doing exactly the right thing.
But we don't know from the article.
Let's pray for them.