Can we pray for the love and conversion of a loved one and know that God will answer that prayer because He said if we pray for anything according to His will He will do it? Or does this fall under the category of God not forcing His will on anyone?
The answer to your first question is no! Your second question seems to expect a no answer and seeks to understand why. Here is the reason.
Anyone Who Calls Will Be Saved
God tells us that no one can be saved who does not call on Jesus Christ,
“Everyone who calls on the name of the Lord will be saved.” How, then, can they call on the one they have not believed in? And how can they believe in the one of whom they have not heard? And how can they hear without someone preaching to them? And how can they preach unless they are sent? As it is written, “How beautiful are the feet of those who bring good news!” (NIV) Romans 10:13-15
And no one will be saved, forgiven of his/her sins, who does not hear the news about Jesus Christ. Salvation comes by hearing the good news and believing in Jesus.
The next important question is who calls on Jesus? According to scripture there is not one person in the world who seeks after God (Romans 3:11). God must pursue them. Jesus makes this very clear. Listen to Jesus’ own words in the gospel of John,
All that the Father gives Me will come to Me, and the one who comes to Me I will by no means cast out.
Therefore I have said to you that no one can come to Me unless it has been granted to him by My Father.
No one can come to Me unless the Father who sent Me draws him. (NKJV) John 6:44, 65, 37
Jesus says no one will come to Him unless God the Father “has already given it” or “already granted it” to him. Ephesians 1:4 agrees with this saying that those who become Christians were selected before the world was created,
Just as He chose us in Him before the foundation of the world . . . (NKJV) Ephesians 1:4
And Matthew 22:14 says, “For many are called, but few are chosen.”
Scripture says that God offers salvation to anyone who calls on Jesus.
For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life. (NIV) John 3:16
Why does God ask us to preach, teach and tell others about Jesus? The answer is it is necessary for them to believe! When they hear, the Holy Spirit can give them understanding.
God asks us to pray that non-Christians (1 Timothy 2:1-4) believe in Jesus in order to be saved. So, pray for your loved one. If he or she believes in Jesus he/she is a Christian. Some believers worry about who God has chosen to be saved. The answer is very easy. If you believe, you were already chosen. Pray that your loved one believes!