The House select committee investigating the Capitol attack on Wednesday issued a second tranche of subpoenas to individuals connected to the rally immediately preceding the 6 January riot, where Donald Trump incited his supporters to commit insurrection.

The new subpoenas for people involved in the march and rally reflects the select committee’s far-reaching mandate to examine whether the attack on the Capitol was planned in advance, according to a source familiar with the matter.

House select committee investigators in total subpoenaed 11 individuals connected to the Trump-supporting organization Women for America First that organized the rally at the Ellipse, including its two co-founders, Amy Kremer and her daughter Kylie Jane Kremer.

“The investigation has revealed credible evidence of your involvement in events within the scope of the select committee’s inquiry,” the chairman of the select committee, Bennie Thompson, said in the subpoena letters.

“Accordingly, the select committee seeks both documents and your deposition testimony regarding these and other matters that are within the scope of the select committee’s inquiry,” Thompson said.

The select committee also subpoenaed other individuals linked to Women for America First: Caroline Wren, Cynthia Lee Chafian, Hannah Salem Stone, Justin Caporale, Katrina Pierson, Lyndon Brentnall, Maggie Mulvaney, Megan Powers, and Tim Unes.

House select committee investigators are specifically questioning Pierson – a spokesperson for Trump’s 2016 presidential campaign – about a 4 January encounter with Trump where the former president asked about a separate event featuring Roger Stone and Ali Alexander.

The select committee, in subpoenaing Pierson and investigating an additional event on the day before the Capitol attack organized by Chafian, is examining connections between the rally leaders and Trump, who helped drive attendance by elevating 6 January as a “wild” protest.

House select committee investigators said in the subpoenas that they believed the 11 people assisted in organizing the rally in support of Trump and his lies about a stolen 2020 election, which incited his supporters to storm the Capitol in his name.

But in a notable addition, the select committee added in the subpoenas that they had been identified as potential witnesses because they communicated with former Trump White House chief of staff Mark Meadows – as well as Trump himself.

The select committee is expected in the coming weeks to authorize still further subpoenas to Trump officials and other individuals connected to the Capitol attack, which could ultimately number in the hundreds, according to a source familiar with internal deliberations.

But it was not immediately clear whether the latest subpoena targets would comply with the orders that compelled them to produce documents by 13 October and appear for depositions in October and November before a select committee that has plainly enraged Trump.

The Guardian first reported on Wednesday that Trump and his advisers are planning to sue to block the release of White House records from his presidency to House investigators over executive privilege claims, according to a source familiar with his planning.

Trump also expects the four aides subpoenaed in the first tranche of orders last week – Meadows, deputy chief Dan Scavino, strategist Steve Bannon and department defense aide Kash Patel – to defy the orders, the source said.

The former president’s efforts to resist the select committee on every front by claiming executive privilege faces steep obstacles, in part because the justice department declined to assert protection over prior testimony related to 6 January.

But the plan to mount legal challenges could ensure the most sensitive Trump White House records are tied up in court for months, delaying the select committee as it aims to produce a final report before the 2022 midterms to shield it from accusations of partisanship.