I'll be honest, my experience of attitudes from orthodox to reform (and particularly reform converts) in some occasions has been particularly poor
As I mentioned, my DM undertook a Reform conversion: over a year of study, essays, evening classes at shul plus additional Hebrew classes (so 3 times a week after work plus weekend study and shul attendance), final assessments. The Rabbi said she was one of the most dedicated and learned students he had ever had
My father was raised in a non frum orthodox household - however his family were very close friends with the Rabbi of their congregation, the eminent Rabbi Felix Carlebach, as was the case with a number of other German Jewish refugees. He was my father's godfather, they would holiday together etc. However he and my grandfather had a falling out when he refused to attend my father's Reform wedding, because my father was marrying a convert. I believe the same happened at my brother's bris, although I believe he apologised afterwards and amends were made.
My paternal family remained very involved in that orthodox congregation - however for obvious reasons I grew up as a member of a Reform congregation. However when the United shul moved to shiny new premises (overseen by my uncle), the Rabbi asked my father if we would be joining the congregation. My father said that would be impossible as his family were not welcome there - to which the Rabbi said my family would always be welcome there. So although my mum and brother and I weren't formally members, there was an understanding that we could sit in the seats bearing the family name at Yom Tov, and my mother was very involved in the League of Jewish women, JNF fundraising, and a well regarded member of the Jewish community. She became quite good friends with the rebbetzin!
However a new rabbi took over this congregation who was a hard liner. So when my mother died, he refused to allow her to be buried in the family plot, because it was under the auspices of a United synagogue and she wasn't an orthodox Jew
The former Rabbi of that congregation was horrified, as he said there was no one in the community who would reasonably object to my mother, who was well liked and respected, being buried in the family plot, but his hands were tied. He came to the house before and after my mother's death. A Lubavitch rabbi who was a good friend of the family came to the house to bless her before she died, and the morning she died he came over to the house to bless her as my brother and I were lying either side of her body waiting for the funeral directors to collect her. He was not permitted by United synagogue law to partake in her Reform funeral service in any way - he broke with the law to walk with us from the ohel to the grave. They both believed compassion was more important than man made rules.
A local Sephardi rabbi had some choice words about the hard line taken by the rabbi who refused to allow my mother to be buried in the family plot (because 'my congregation need to know they're buried with other Jewish people') - he said that there were people buried in that section of the cemetery who weren't even Jewish!
We had 3 orthodox rabbis all trying to persuade the Rabbi to change his mind, but he refused
We purchased a plot through the reform synagogue where my family were members, and my father will be buried there with her - sadly not with the rest of his family, because man made rules deemed that she wasn't Jewish enough.