I think such advice would not only be accepted but expected, particularly from an older woman acting in an almost maternal capacity as Lady Russell was; and that young people needed in general to be advised by their 'elders and betters' seems to have been a given. How welcome such advice would be, or how well heeded, would, I think, depend on a combination of factors, including the young lady's personality and the degree of respect and affection she felt for the advisor.

If JA's novels are at all a reflection of reality in this respect, we have some examples: In MP we have Aunt Norris encouraging Maria to marry Rushworth (to which I have no doubt Maria would have objected had she not had the same end in view herself), and everyone encouraging if not browbeating Fanny to marry Crawford. In S&S, Elinor warns Marianne to be more cautious with Willoughby, and Sir John & Mrs Jennings consider the love affairs of the Miss Dashwoods fair game for sport and speculation. In Emma, Knightley warns Emma about Frank Churchill, asking if she is sure she understands his relationship to Jane Fairfax. In P&P, Elizabeth pays no attention to her mother's insistence that she marry Mr Collins, but she is greatly distressed by her father's objections to her marrying Darcy - though SHE is able to persuade HIM in the end. She ignores Caroline Bingley's warning about Wickham, but is much more open to her Aunt Gardiner's caution about the same gentleman. As this is cited as 'a wonderful instance of advice being given on such a point without being resented', however, one might conclude rebellion was not uncommon.