Filed GC for parents, pending i-130 approval

[bp11]

Hi- I am a USC and filed my parents GC in Dec 2018. The I-130 is still pending approval but my parents are planning to visit USA for a wedding next month. They have 10 years multiple visa already and have visited multiple times. Should that be a problem?
Also, what to do when I get I-130 approval while they are still in USA. I dont want to transfer the case from Consular processing to AOS. Please help