Which one is better or grammaratically correct?

faisalkhanThe sentence below does not follow the "subject+ verb+ object" rule like the above one. Is that OK?

It does follow SVO. Why do you say it doesn't?
marriage registration = subject
can play = verb
a significant role = object

I am talking about this sentence "To help them in this situation, marriage registration can play a significant role."

The subject precedes the verb and the verb precedes the object in that sentence, as AS told you.

faisalkhanI am talking about this sentence "To help them in this situation, marriage registration can play a significant role."

Yes, I am talking about that sentence, too. It is SVO order.
Maybe you are confused about the subject, verb and object.

faisalkhanTo help them in this situation, marriage registration can play a significant role.

To help them in this situation - an adverbial (a non-finite adverbial clause of purpose ~ [in order] To help them...)
marriage registration - a subject;
can play - a predicator;
a significant role - a direct object.

Anonymouscan play - a predicator;

So as not to confuse the poster, I cite the definition of "predictor."

predicator:
(in systemic grammar) the part of a sentence or clause containing the verbal group; one of the four or five major components into which clauses can be divided, the others being subject, object, adjunct, and (in some versions of the