I have questions about my kid's scores individually and concerns about siblings/parenting in general. The kids are just finishing 4th grade

First DD10. I only have her Spring MAPs but I remember that she has improved in both areas. Reading was 224, 93 percentile. Math was 235, 96 percentile. She is a 4.0 student but studies very methodically and works hard. I'm thinking of an online Duke Word Roots/reading/writing course for enrichment for her this summer. She was tested for GATE 2 years ago but did not get in - she scored 88% on whatever test they gave her. Her teacher this year is encouraging us to have her tested again. She loves reading the Lemony Snickets series.

DS10 - in GATE and we have applied for a program which will place him with 5th & 6th graders in the fall but is supposed to accelerate students in each subject as needed. Should hear soon if he gets accepted. Here are his MAPS;
Reading Math
Fall 224 Fall 238
Winter 231 Winter 246
Spring 233 Spring 247

He really loves math and I know the 247 is somewhere in the 99th percentile but I don't know how to figure out where it falls. I'm worried about the plateaus in both subjects. He says he isn't learning anything new. He's registered for EPGY over summer in accelerated 5th-6th grade math. Anyone with experience with EPGY? We may apply for DA in the future - I don't know if he'll qualify but he wants to go all out. He will take the EXPLORE in Oct. WISC IV is 136 in Dec, highest subscore was matrix reasoning - 19.

Now the parenting part. They have been kept together since K at our request. My struggle is being supportive of each of them but they are very competitive and constantly compare daily work, test scores, etc. They both do sports and used to do the same sports but we have separated them in that area. My daughter often feels inferior because in school she usually scores just under her brother but she is a bright, beautiful girl who is a 5-time state gymnastics champion!

Anyone with similar issues with siblings? I want them EACH to feel joyful at their accomplishments!