What are the rules of Concord in English Language

Concord
Concord in English can be defined as the mutual relationship between the grammatical element or word classes in sentences. The term concord can be given a primary definition as the relationship between subjects and verbs in sentences. The subject may be noun or pronouns while the verb is the binding element. The relationship extends to pronouns and their antecedents.
Law of Concord
The law of Concord states that a singular subjects should be used with a singular verbs while a plural subject is used with the plural verbs. This must be done considering pronouns and their antecedents in number, gender, person and time of event express by the use of verbs.
This law can be expressed with the used of the following sentences
Example:
The boy plays football.
He plays football.
The law of Concord or agreement can be expressed in a tabular form as shown below.
Singular Plural
Noun(s) – S. + S
Verbs. + S. – S
Example:
The boy plays football.
The boys play football.
To determine the subject in a sentence, find out the subject and as yourself the following questions.
(1) Is the subject singular?
(2) Is the subject plural?
Besides, the verb would also be searched out to determine whether it is singular or plural to agree with the subject.

Rule 1
If a determiner or a qualifier is used in a sentence after the subject, the determiner or qualifier should not control the verb. Instead the subject which operates far away from the verb should control the verb.
Example:
The furnishings of the pilgrim’s home are as expensive as the home itself.
The waste matter from our goats is useful manure.

Rule 2
If two complementary subjects are used in a sentence, the verb must always remain in singular form. However, one of the subject may or may not be used with the determiner or qualifier. In such situation the first subject is often used with determiner or qualifier.
Example:
My wife and boss has travelled to Abuja.
The principal and secretary of the organisation is at the trade fare ground.

Rule 3
If two different subjects are used in a sentence which are not complementary subject even if these subjects are not used with determiner, the verb remains in the plural form. Besides, if two subjects are used in determiners or qualifier, the verb should remain in the plural.
Example:
The manager and the director have travelled to New York.
My wife and my boss have travelled.

Rule 4
If the phrase “One of the” begins a sentence the verb should remain in the singular form but if “one of the” is embedded in a sentence, the verb should be in the plural form because there is always a compulsory use of relative pronouns.
Example:
One of the girls talks too much.
Grace is one of the girls who talk too much.

Rule 5
Concord with Indefinite
If indefinite pronouns are used in an English sentence, they should always go with singular verbs except the subject of the sentence is different from indefinite pronouns are each, one, some, any etc
Example:
Each of us is to go to the church.
We each has been given a book.
Somebody is coming.

Rule 6
Concord with correlatives:
When correlatives verbs are used in a sentences, the singular verbs should be used to agree to the subject, number and person but if the subject are plural the verb should also be in plural form.
Example:
Either the boy or the girl is invited to the party.
Either the boys or the girls are invited to the party.
Not only the boys but also the girls are invited to the party.
*Note: The law of proximity or nearness states that the correlatives conjunctions are used with two subject different number, the subject which is near to the verb controls the verb.
Either the boys or the girls are invited to the birthday party
Neither the woman nor the children have been immunised.

Rule 7
If a noun or a pronoun begins a sentence followed by an adverb such as with, as well as, together with, including etc. The subject controls the verb and not the determiner contained in the word/adverb.
Examples
Janet with her in law brothers and uncle has travelled to Canada.
The students including their teachers are in class.

Rule 8
If two nouns are used in a sentence one is used as the subject while the other is used as the predicate. The verb should be made to agree with the subject and not with the predicate.
Example
Ladies fingers are my specialty.
My specialty is ladies fingers.