Thanks for your reply and apologies for the delay.
As the Executor, you are entitled to make the decisions relating to the Estate and indeed have the legal power to do so. Therefore, your Solicitor is under a duty to take your instructions, provided they are reasonable and not illegal, and carry out such instructions.
It is normal for a beneficiary to "give up" their share of a property in return for the other beneficiaries paying her for her due proportion of the value of the property.
It would, however, be normal for the Executor to come to an agreement with the other beneficiaries, as it may take the Solicitor a lot of time (and expense to the Estate) in negotiating the deal. It would therefore be best if you can come to an agreement with your siblings, although I appreciate this may be difficult for you.
You need to agree how much money your share in the property is worth- at the end of the day, all of the siblings will need to agree on this figure, to enable the transfer to proceed. It would be normal for 3 valuations of the property to be obtained, and the middle valuation be taken as the valuation of the property.
If you are not able to speak/write to your siblings to get an agreemet, your Solicitor has no authority not to carry out your wishes and contact them herself. Yes, it will be more expensive for the Estate to do this, but it sounds to me, that she is just trying to avoid any extra work.
I would hope that, as she has opened your letter addressed to the Senior Partner, that she will now be doing all she can not to cause any further complaint. However, if you still face problems with her, I would suggest a further hand delivered letter to the Senior Partner, and failing that you shoud speak to the Solicitors Regulation Authority who oversee complaints about Solicitors.
I hope this assists and sets out the position to you.
If I have helped, I would be grateful if you could rate my answer.