The acquaintances who we like most are those that flatter ..

The acquaintances who/whom we like most are those that flatter us best.

Please help with the above SC sentence. My understanding is as below. Also I have mentioned some doubts related to pronouns used in this sentence.

In this sentence Pronouns are : who/whom, we, those and that.

My question is related to these pronouns.
1. First of all we will choose who/whom. In the relative clause 'who/whom we like most', the
subject = we
verb = like
Since here who/whom is the object of verb in the relative pronoun we use whom.
The acquaintances whom we like most are those that flatter us best.

2. Pronoun antecedent:
I am sure whom and that refer to the antecedent acquaintances.
Those refers to acquaintances 'we like most' so does that mean acquaintance is the antecedent of those as well?

3. As per MGMAT guide, 'that' on GMAT can not be used for modifying people. So should it be replaced with who (subject of relative clause 'who flatter us best')
The acquaintances whom we like most are those who flatter us best.

The acquaintances who/whom we like most are those that flatter us best.
In this sentence Pronouns are : who/whom, we, those and that.
My question is related to these pronouns.

1. First of all we will choose who/whom. In the relative clause 'who/whom we like most', the
subject = we
verb = like
Since here who/whom is the object of verb in the relative pronoun we use whom.
The acquaintances whom we like most are those that flatter us best.

Usage of Who/ Whom:
Who is used as the subject of the clause.
Whom is used as the object of the clause.
In the first part of the sentence, Whom is correct as it is the object.


2. Pronoun antecedent:
I am sure whom and that refer to the antecedent acquaintances.
Those refers to acquaintances 'we like most' so does that mean acquaintance is the antecedent of those as well?

"That" do not refer to the antecedent. It is acting as the Connector. "Those" refer to the antecedent

3. As per MGMAT guide, 'that' on GMAT cannot be used for modifying people. So should it be replaced with who (subject of relative clause 'who flatter us best')
The acquaintances whom we like most are those who flatter us best.

Few Rules:
Who, Whom, can modify only people.
Which, That can modify only things.
Whose can modify both things and People.

Now in the second part of the sentence, Those who flatter us best - "Who" is correct as it is the subject of the clause.